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169 Ch 28_lecture_presentation

  1. 1. © 2012 Pearson Education, Inc. PowerPoint® Lecture Presentations prepared by Jason LaPres Lone Star College—North Harris 28 The Reproductive System
  2. 2. © 2012 Pearson Education, Inc. An Introduction to the Reproductive System • Learning Outcomes • 28-1 List the basic components of the human reproductive system, and summarize the functions of each. • 28-2 Describe the components of the male reproductive system and the roles played by the reproductive tract and accessory glands in producing spermatozoa; specify the composition of semen; and summarize the hormonal mechanisms that regulate male reproductive functions.
  3. 3. © 2012 Pearson Education, Inc. An Introduction to the Reproductive System • Learning Outcomes • 28-3 Describe the components of the female reproductive system and the ovarian roles in oogenesis; explain the complete ovarian and uterine cycles; outline the histology, anatomy, and functions of the vagina; and summarize all aspects of the female reproductive cycle. • 28-4 Discuss the physiology of sexual intercourse in males and females.
  4. 4. © 2012 Pearson Education, Inc. An Introduction to the Reproductive System • Learning Outcomes • 28-5 Describe the reproductive system changes that occur with aging. • 28-6 Give examples of interactions between the reproductive system and each of the other organ systems.
  5. 5. © 2012 Pearson Education, Inc. An Introduction to the Reproductive System • The Reproductive System • Is the only system that is not essential to the life of the individual • Does affect other systems • The male and female reproductive organs • Produce and store specialized reproductive cells that combine to form new individuals • Reproductive organs • Also secrete hormones that play major roles in the maintenance of normal sexual function
  6. 6. © 2012 Pearson Education, Inc. 28-1 Structures of the Reproductive System • Reproductive Structures • Gonads are organs that produce gametes and hormones • Ducts receive and transport gametes • Accessory glands secrete fluids into ducts • Perineal structures collectively known as external genitalia
  7. 7. © 2012 Pearson Education, Inc. 28-1 Structures of the Reproductive System • The Reproductive Tract • Includes all chambers and passageways that connect ducts to the exterior of the body • Male and Female Reproductive Systems • Are functionally different • Female produces one gamete per month • Retains and nurtures zygote • Male produces large quantities of gametes • Produces 1/2 billion sperm per day
  8. 8. © 2012 Pearson Education, Inc. 28-1 Structures of the Reproductive System • The Male Reproductive System • Testes or male gonads • Secrete male sex hormones (androgens) • Produce male gametes (spermatozoa or sperm)
  9. 9. © 2012 Pearson Education, Inc. 28-1 Structures of the Reproductive System • The Female Reproductive System • Ovaries or female gonads • Release one immature gamete (oocyte) per month • Produce hormones • Uterine tubes • Carry oocytes to uterus - if sperm reaches oocyte, fertilization is initiated and oocyte matures into ovum • Uterus • Encloses and supports developing embryo • Vagina • Connects uterus with exterior
  10. 10. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Pathway of Spermatozoa • Testis • Epididymis • Ductus deferens (vas deferens) • Ejaculatory duct • Urethra
  11. 11. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Accessory Organs • Secrete fluids into ejaculatory ducts and urethra • Seminal glands (vesicles) • Prostate gland • Bulbo-urethral glands
  12. 12. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • External Genitalia • Scrotum • Encloses testes • Penis • Erectile organ • Contains distal portion of urethra
  13. 13. © 2012 Pearson Education, Inc. Figure 28-1 The Male Reproductive System Scrotum External urethral orifice Testis Epididymis Penis Ductus deferens Spongy urethra Corpus spongiosum Corpus cavernosum Prostatic urethra Pubic symphysis Urinary bladder
  14. 14. © 2012 Pearson Education, Inc. Figure 28-1 The Male Reproductive System Ejaculatory duct Bulbo-urethral gland Anus Prostate gland Seminal gland Rectum Ureter
  15. 15. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Testes • Egg shaped • 5 cm long, 3 cm wide, 2.5 cm thick (2 in. × 1.2 in. × 1 in.) • Each weighs 10–15 g (0.35–0.53 oz) • Hang in scrotum
  16. 16. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Scrotum • Is a fleshy pouch • Suspended inferior to perineum • Anterior to anus • Posterior to base of penis
  17. 17. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Descent of the Testes • Testes form inside body cavity adjacent to kidneys • Gubernaculum testis • Is a bundle of connective tissue fibers • Extends from testis to pockets of peritoneum • Locks testes in position (near anterior abdominal wall) as fetus grows
  18. 18. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Descent of the Testes • During seventh month • Fetus grows rapidly • Circulating hormones • Stimulate contraction of gubernaculum testis • Each testis: • Moves through abdominal musculature • Is accompanied by pockets of peritoneal cavity
  19. 19. © 2012 Pearson Education, Inc. Figure 28-2a The Descent of the Testes Sagittal sectional views of the positional changes involved in the descent of the right testis. Birth 3 months 2 months 5 mm 5 mmScrotum Testis Pubis Penis Umbilical cord Peritoneum Colon Testis Gubernaculum testis 5 mm
  20. 20. © 2012 Pearson Education, Inc. Figure 28-2b The Descent of the Testes Frontal views showing the descent of the testes and the formation of the spermatic cords. 2 months 3 months 4 months Diaphragmatic ligament Mesonephric duct Developing kidneys Gubernaculum testis Gonads Diaphragmatic ligament Kidney Testis Epididymis Testis Epididymis Urinary bladder
  21. 21. © 2012 Pearson Education, Inc. Figure 28-2b The Descent of the Testes Frontal views showing the descent of the testes and the formation of the spermatic cords. 7 months Birth Urinary bladder Scrotum (opened) Testicular artery and vein Spermatic cord Ureter Ureter Superficial inguinal ring Scrotal cavity (opened) lined by tunica vaginalis Testicular artery and vein Gubernaculum testis Testis Epididymis Vas deferens
  22. 22. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Accessory Structures • Accompany testis during descent • Form body of spermatic cord • Ductus deferens • Testicular blood vessels, nerves, and lymphatic vessels
  23. 23. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Spermatic Cords • Extend between abdominopelvic cavity and testes • Consist of layers of fascia and muscle • Enclose ductus deferens, blood vessels, nerves, and lymphatic vessels of testes • Pass through inguinal canal • Are passageways through abdominal musculature • Form during development as testes descend into scrotum • Descend into scrotum
  24. 24. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Blood Vessels of Testes • Deferential artery • Testicular artery • Pampiniform plexus of testicular vein • Nerves of Testes • Branches of genitofemoral nerve • From lumbar plexus
  25. 25. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Male Inguinal Hernias • Are protrusions of visceral tissues into inguinal canal • Spermatic cord (in closed inguinal canal) • Causes weak point in abdominal wall • Female Inguinal Canals • Are very small • Contain ilioinguinal nerves and round ligaments of uterus
  26. 26. © 2012 Pearson Education, Inc. Figure 28-3 The Male Reproductive System in Anterior View Inguinal canal Spermatic cord Urinary bladder Genitofemoral nerve Deferential artery Ductus deferens Pampiniform plexus Testicular artery Epididymis Scrotal cavity Testis (covered by visceral layer of tunica vaginalis) Parietal layer of tunica vaginalis (inner lining of cremaster, facing scrotal cavity)
  27. 27. © 2012 Pearson Education, Inc. Figure 28-3 The Male Reproductive System in Anterior View Raphe Scrotal skin (cut) Dartos muscle Superficial scrotal fascia Cremaster muscle with cremasteric fascia Scrotal septum Spermatic cord Superficial inguinal ring Inguinal ligament Penis Testicular vein Testicular artery
  28. 28. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Scrotum and the Position of the Testes • Is divided into two chambers, or scrotal cavities • Each testis lies in a separate scrotal chamber • Raphe • Is a raised thickening in scrotal surface • Marks partition of two scrotal chambers
  29. 29. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Tunica Vaginalis • Is a serous membrane • Lines scrotal cavity • Reduces friction between opposing surfaces • Parietal (scrotal) • Visceral (testicular)
  30. 30. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Dartos Muscle • Is a layer of smooth muscle in dermis of scrotum • Causes characteristic wrinkling of scrotal surface • The Cremaster Muscle • Is a layer of skeletal muscle deep to dermis • Tenses scrotum and pulls testes closer to body (temperature regulation)
  31. 31. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Temperature Regulation • Normal sperm development in testes • Requires temperatures 1.1°C (2°F) lower than body temperature • Muscles relax or contract • To move testes away or toward body • To maintain acceptable testicular temperatures
  32. 32. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Structure of the Testes • Tunica Albuginea • Is deep to tunica vaginalis • A dense layer of connective tissue rich in collagen fibers • Continuous with fibers surrounding epididymis • Fibers extend into substance of testis and form fibrous partitions, or septa, that converge near entrance to epididymis • Supports blood and lymphatic vessels of testis and efferent ductules
  33. 33. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Histology of the Testes • Septa subdivide testis into lobules • Lobules contain about 800 slender and tightly coiled seminiferous tubules • Produce sperm • Each is about 80 cm (32 in.) long • Testis contains about 1/2 mile of tightly coiled seminiferous tubules • Form a loop connected to rete testis, a network of passageways
  34. 34. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Efferent Ductules • 15–20 large efferent ductules • Connect rete testis to epididymis
  35. 35. © 2012 Pearson Education, Inc. Figure 28-4a The Structure of the Testes A transverse section of the scrotum and testes Raphe Lobule Septa Scrotal cavity Tunica albuginea Tunica vaginalis Cremaster muscle Superficial scrotal fascia Dartos muscle Skin Scrotum Efferent ductule Epididymis Ductus deferens Septa Mediastinum of testis Seminiferous tubules Straight tubule Rete testis
  36. 36. © 2012 Pearson Education, Inc. Figure 28-4b The Structure of the Testes A section through a testis Septa Mediastinum of testis Seminiferous tubules Straight tubule Rete testis Testis LM × 26 Raphe Lobule Septa Scrotal cavity Tunica albuginea Tunica vaginalis Cremaster muscle Superficial scrotal fascia Dartos muscle Skin Scrotum Efferent ductule Epididymis Ductus deferens
  37. 37. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Connective Tissue Capsules • Surround tubules • Areolar tissue fills spaces between tubules • Within those spaces, there are: • Blood vessels • Large interstitial cells (Leydig cells) • Produce androgens, dominant male sex hormones • Testosterone is the most important androgen
  38. 38. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Spermatogenesis • Is the process of sperm production • Begins at outermost cell layer in seminiferous tubules • Proceeds toward lumen
  39. 39. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Cells of Spermatogenesis • Spermatogonia (stem cells) divide by mitosis to produce two daughter cells • One remains as spermatogonium • Second differentiates into primary spermatocyte • Primary spermatocytes begin meiosis and form secondary spermatocytes
  40. 40. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Cells of Spermatogenesis • Secondary spermatocytes differentiate into spermatids (immature gametes) • Spermatids • Differentiate into spermatozoa • Spermatozoa • Lose contact with wall of seminiferous tubule • Enter fluid in lumen
  41. 41. © 2012 Pearson Education, Inc. Figure 28-5a The Seminiferous Tubules A section through a coiled seminiferous tubule. LM × 75Seminiferous tubules Seminiferous tubule containing late spermatids Seminiferous tubule containing spermatozoa Seminiferous tubule containing early spermatids
  42. 42. © 2012 Pearson Education, Inc. Figure 28-5b The Seminiferous Tubules A cross section through a single tubule. LM × 350 Heads of maturing spermatozoa Spermatids Spermatogonia Nurse cells Interstitial cells Lumen Dividing spermatocytes Seminiferous tubule
  43. 43. © 2012 Pearson Education, Inc. Figure 28-5c The Seminiferous Tubules Nurse cells surround the stem cells of the tubule and support the developing spermatocytes and spermatids. Interstitial cells Spermatogonium Spermatozoa Lumen Spermatid CapillaryDividing spermatocytes Nurse cell
  44. 44. © 2012 Pearson Education, Inc. Figure 28-5d The Seminiferous Tubules Stages in spermatogenesis in the wall of a seminiferous tubule. Basal compartment Spermatogonium Capillary Nuclei of nurse cells Primary spermatocyte preparing for meiosis I Secondary spermatocyte Spermatids beginning spermiogenesis Spermatids completing spermiogenesis Secondary spermatocyte in meiosis II Level of blood–testis barrier Connective tissue capsule Luminal compartment Initial spermiogenesis Fibroblast LUMEN Interstitial cells
  45. 45. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Contents of Seminiferous Tubules • Spermatogonia • Spermatocytes at various stages of meiosis • Spermatids • Spermatozoa • Large nurse cells (also called sustentacular cells or Sertoli cells) • Are attached to tubular capsule • Extend to lumen between other types of cells
  46. 46. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Spermatogenesis • Involves three integrated processes 1. Mitosis 2. Meiosis 3. Spermiogenesis
  47. 47. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Mitosis • Is part of somatic cell division • Produces two diploid daughter cells • Both have identical pairs of chromosomes
  48. 48. © 2012 Pearson Education, Inc. Figure 28-6a Chromosomes in Mitosis and Meiosis Mitosis. The fates of three representative chromosome pairs during mitosis 21 Daughter cells Chromosomes of daughter cell 1 Chromosomes of daughter cell 2 Chromosome duplication Chromosomes Cell
  49. 49. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Meiosis • Is a special form of cell division involved only in production of gametes • Spermatozoa in males • Oocytes in females • Gametes contain 23 chromosomes, half the normal amount • Fusion of male and female gametes produces zygote with 46 chromosomes • In seminiferous tubules: • Begins with primary spermatocytes • Produces spermatids (undifferentiated male gametes)
  50. 50. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Spermiogenesis • Begins with spermatids • Small, relatively unspecialized cells • Involves major structural changes • Spermatids differentiate into mature spermatozoa • Highly specialized cells
  51. 51. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Mitosis and Meiosis • Meiosis I and meiosis II • Produce four haploid cells, each with 23 chromosomes
  52. 52. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Mitosis and Meiosis • Prophase I • Chromosomes condense • Each chromosome has two chromatids • Synapsis • Maternal and paternal chromosomes come together • Four matched chromatids form tetrad • Crossing over: exchange of genetic material that increases genetic variation among offspring
  53. 53. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Mitosis and Meiosis • Metaphase I • Tetrads line up along metaphase plate • Independent assortment • As each tetrad splits: • Maternal and paternal components are randomly distributed
  54. 54. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Mitosis and Meiosis • Anaphase I • Maternal and paternal chromosomes separate • Each daughter cell receives whole chromosome • Maternal or paternal
  55. 55. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Mitosis and Meiosis • Telophase I ends • With formation of two daughter cells • With unique combinations of chromosomes • Both cells contain 23 chromosomes with two chromatids each (reductional division)
  56. 56. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Mitosis and Meiosis • Interphase • Separates meiosis I and meiosis II • Is very brief • DNA is not replicated
  57. 57. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Mitosis and Meiosis • Meiosis II • Proceeds through prophase II and metaphase II • Anaphase II • Duplicate chromatids separate • Telophase II • Yields four cells, each containing 23 chromosomes (equational division)
  58. 58. © 2012 Pearson Education, Inc. Figure 28-6a Chromosomes in Mitosis and Meiosis Mitosis. The fates of three representative chromosome pairs during mitosis 21 Daughter cells Chromosomes of daughter cell 1 Chromosomes of daughter cell 2 Chromosome duplication Chromosomes Cell
  59. 59. © 2012 Pearson Education, Inc. Figure 28-6b Chromosomes in Mitosis and Meiosis Meiosis. The fates of three representative chromosome pairs during the two stages of meiosis Chromosomes Tetrad Cell Chromosome duplication, synapsis, and tetrad formation Meiosis I Meiosis II Chromosomes of gametes Gametes 1 2 3 41 2 3 4
  60. 60. © 2012 Pearson Education, Inc. Figure 28-7 Spermatogenesis Spermatogenesis Mitosis of spermatogonium Each division of a diploid spermatogonium produces two daughter cells. One is a spermatogonium that remains in contact with the basement membrane of the tubule, and the other is a primary spermatocyte that is displaced toward the lumen. Primary spermatocyte (diploid)
  61. 61. © 2012 Pearson Education, Inc. Figure 28-7 Spermatogenesis Spermatogenesis Meiosis I Prior to the start of Meiosis I, each primary spermatocyte contains 46 individual chromosomes. At the end of meiosis I, the daughter cells are called secondary spermatocytes. Every secondary spermatocyte contains 23 chromosomes, each of which consists of a pair of duplicate chromatids. DNA replication Primary spermatocyte in late Prophase I Synapsis and tetrad formation Secondary spermatocytes
  62. 62. © 2012 Pearson Education, Inc. Figure 28-7 Spermatogenesis Spermatogenesis Meiosis II The secondary spermatocytes soon enter meiosis II, which yields four haploid spermatids, each containing 23 chromosomes. For each primary spermatocyte that enters meiosis, four spermatids are produced. Spermatids (haploid)
  63. 63. © 2012 Pearson Education, Inc. Figure 28-7 Spermatogenesis Spermiogenesis (physical maturation) In spermiogenesis, the last step of spermatogenesis, each spermatid matures into a single spermatozoon, or sperm. The process of spermiogenesis takes roughly 5 weeks to complete. Spermatozoa (haploid) Spermatogenesis
  64. 64. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Spermiogenesis • Is the last step of spermatogenesis • Each spermatid matures into one spermatozoon (sperm) • Attached to cytoplasm of nurse cells
  65. 65. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Spermiation • At spermiation, a spermatozoon: • Loses attachment to nurse cell • Enters lumen of seminiferous tubule • Spermatogonial division to spermiation • Takes about 9 weeks
  66. 66. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Nurse Cells • Affect: • Mitosis • Meiosis • Spermiogenesis in seminiferous tubules
  67. 67. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Six Major Functions of Nurse Cells 1. Maintain blood–testis barrier 2. Support mitosis and meiosis 3. Support spermiogenesis 4. Secrete inhibin 5. Secrete androgen-binding protein (ABP) 6. Secrete Müllerian-inhibiting factor (MIF)
  68. 68. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Maintenance of Blood–Testis Barrier • Blood–testis barrier isolates seminiferous tubules • Nurse cells are joined by tight junctions that divide seminiferous tubule into compartments • Outer basal compartment contains spermatogonia • Inner luminal compartment is where meiosis and spermiogenesis occur
  69. 69. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Support of Mitosis and Meiosis • Nurse cells are stimulated by: • Follicle-stimulating hormone (FSH) • Testosterone • Stimulated nurse cells promote: • Division of spermatogonia • Meiotic divisions of spermatocytes
  70. 70. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Support of Spermiogenesis • Nurse cells • Surround and enfold spermatids • Provide nutrients and chemical stimuli for development • Phagocytize cytoplasm shed by developing spermatids
  71. 71. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Secretion of Inhibin • Inhibin • Is a peptide hormone secreted by nurse cells in response to factors released by spermatozoa • Depresses: • Pituitary production of FSH • Hypothalamic secretion of GnRH • Regulation of FSH and GnRH by inhibin: • Gives nurse cells feedback control of spermatogenesis • After division, increases inhibin production
  72. 72. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Secretion of Androgen-Binding Protein (ABP) • Androgen-Binding Protein (ABP) • Binds androgens (primarily testosterone) • In seminiferous tubule fluid • Is important in: • Elevating androgen in seminiferous tubules • Stimulating spermiogenesis • Production of ABP is stimulated by FSH
  73. 73. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Secretion of Müllerian-Inhibiting Factor (MIF) • Müllerian-Inhibiting Factor (MIF) • Is secreted by nurse cells in developing testes • Causes regression of fetal Müllerian (paramesonephric) ducts • Help form uterine tubes and uterus in females • In males, inadequate MIF production leads to: • Retention of ducts • Failure of testes to descend into scrotum
  74. 74. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Anatomy of a Spermatozoon • Head • Neck (attaches head to middle piece) • Middle piece • Tail
  75. 75. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Anatomy of a Spermatozoon • Head • A flattened ellipse that contains nucleus and chromosomes • Acrosome • A cap-like compartment at tip of head • A membranous compartment that contains enzymes essential to fertilization • Made of fused saccules of spermatid’s Golgi apparatus
  76. 76. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Anatomy of a Spermatozoon • Middle piece • Attached to head by short neck • Contains mitochondria • In spiral around microtubules • Activity provides ATP to move tail
  77. 77. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Anatomy of a Spermatozoon • Tail • Is the only flagellum in the human body • Is a whiplike organelle • Moves cell from one place to another • Has complex, corkscrew motion
  78. 78. © 2012 Pearson Education, Inc. Figure 28-8 Spermiogenesis and Spermatozoon Structure Spermatid (week 1) Golgi apparatus Mitochondria Nucleus Acrosomal vesicle Spermiogenesis. The differentiation of a spermatid into a spermatozoon. This differentiation process is completed in approximately 5 weeks. Acrosome Nucleus Acrosome Shed cytoplasm
  79. 79. © 2012 Pearson Education, Inc. Figure 28-8 Spermiogenesis and Spermatozoon Structure Spermatozoon (week 5) Tail (55 µm) Middle piece (5 µm) Neck (1 µm) Head (5 µm) Acrosome Nucleus Centrioles Mitochondrial spiral Fibrous sheath of flagellum Spermatozoa SEM × 780
  80. 80. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Mature Spermatozoon • Lacks: • Endoplasmic reticulum • Golgi apparatus • Lysosomes and peroxisomes • Inclusions and other intracellular structures • Loss of these organelles reduces sperm size and mass • Sperm must absorb nutrients (fructose) from surrounding fluid
  81. 81. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Male Reproductive Tract • Sperm Maturation • Testes produce physically mature spermatozoa that CANNOT fertilize an oocyte • Other parts of reproductive system are responsible for: • Functional maturation, nourishment, storage, and transport
  82. 82. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Male Reproductive Tract • Sperm Maturation • Spermatozoa • Detach from nurse cells • Are free in lumen of seminiferous tubule • Are functionally immature • Are incapable of locomotion or fertilization • Are moved by cilia lining efferent ductules into the epididymis
  83. 83. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Epididymis • Is the start of male reproductive tract • Is a coiled tube almost 7 m (23 ft) long • Bound to posterior border of testis • Has a head, a body, and a tail
  84. 84. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Epididymis Head • Is proximal to the testis • Receives spermatozoa from efferent ductules • Epididymis Body • From last efferent ductule to posterior margin of testis • Epididymis Tail • Begins near inferior border of testis where number of coils decreases • Re-curves and ascends to connection with ductus deferens • Primary storage location of spermatozoa
  85. 85. © 2012 Pearson Education, Inc. Figure 28-9a The Epididymis A diagrammatic view of the head, body, and tail of an epididymis Spermatic cord Body of epididymis Ductus deferens Tail of epididymis Head of epididymis Efferent ductules Rete testis Seminiferous tubule Tunica albuginea Scrotal cavity Testis
  86. 86. © 2012 Pearson Education, Inc. Figure 28-9b The Epididymis Epithelial features, especially the elongate stereocilia characteristic of the epididymis Epididymis LM × 304 Stereocilia Pseudostratified columnar epithelium of epididymis Flagella of spermatozoa in lumen of epididymis
  87. 87. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Three Functions of the Epididymis 1. Monitors and adjusts fluid produced by seminiferous tubules 2. Recycles damaged spermatozoa 3. Stores and protects spermatozoa • Facilitates functional maturation
  88. 88. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Spermatozoa Leaving Epididymis • Are mature, but remain immobile • To become motile (actively swimming) and functional: • Spermatozoa undergo capacitation
  89. 89. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Two Steps in Capacitation 1. Spermatozoa become motile • When mixed with secretions of seminal glands 1. Spermatozoa become capable of fertilization • When exposed to female reproductive tract
  90. 90. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Ductus Deferens (Vas Deferens) • Is 40–45 cm (16–18 in.) long • Begins at tail of the epididymis and, as part of spermatic cord, ascends through inguinal canal • Curves inferiorly along urinary bladder • Toward prostate gland and seminal glands • Lumen enlarges into ampulla • Wall contains thick layer of smooth muscle
  91. 91. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Ductus Deferens • Is lined by ciliated epithelium • Peristaltic contractions propel spermatozoa and fluid • Can store spermatozoa for several months • In state of suspended animation (low metabolic rates)
  92. 92. © 2012 Pearson Education, Inc. Figure 28-10a The Ductus Deferens and Accessory Glands A posterior view of the urinary bladder and prostate gland, showing subdivisions of the ductus deferens in relation to surrounding structures. Bulbo-urethral glands Urogenital diaphragm Prostatic urethra Prostate gland Ejaculatory duct Duct of seminal gland Ampulla of ductus deferens Seminal gland Ductus deferens Ureter Urinary bladder
  93. 93. © 2012 Pearson Education, Inc. Figure 28-10b The Ductus Deferens and Accessory Glands Light micrograph showing the thick layers of smooth muscle in the wall of the ductus deferens. LM × 120 Smooth muscle Lumen of ductus deferens
  94. 94. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Ejaculatory Duct • Is a short passageway (2 cm; less than 1 in.) • At junction of ampulla and seminal gland duct • Penetrates wall of prostate gland • Empties into urethra
  95. 95. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Urethra • Is used by urinary and reproductive systems • Extends 18–20 cm (7–8 in.) from urinary bladder to tip of penis • Is divided into three regions 1. Prostatic 2. Membranous 3. Spongy
  96. 96. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Accessory Glands • Produce semen, which is a mixture of secretions from many glands • Each with distinctive biochemical characteristics • Important glands include: 1. Seminal glands 2. Prostate gland 3. Bulbo-urethral glands
  97. 97. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Four Major Functions of Male Glands 1. Activating spermatozoa 2. Providing nutrients spermatozoa need for motility 3. Propelling spermatozoa and fluids along reproductive tract • Mainly by peristaltic contractions 3. Producing buffers • To counteract acidity of urethral and vaginal environments
  98. 98. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Seminal Glands (Seminal Vesicles) • Each gland is about 15 cm (6 in.) long with short side branches from body • Are tubular glands coiled and folded into 5 cm by 2.5 cm (2 in. × 1 in.) mass • Are extremely active secretory glands • Produce about 60% of semen volume
  99. 99. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Seminal Fluid • Has same osmotic concentration as blood plasma but different composition • High concentrations of fructose easily metabolized by spermatozoa • Prostaglandins stimulate smooth muscle contractions (male and female) • Fibrinogen forms temporary clot in vagina • Is slightly alkaline • To neutralize acids in prostate gland and vagina
  100. 100. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Seminal Fluid • Initiates first step in capacitation • Spermatozoa begin beating flagella, become highly motile • Is discharged into ejaculatory duct at emission • When peristaltic contractions are under way • Contractions are controlled by sympathetic nervous system
  101. 101. © 2012 Pearson Education, Inc. Figure 28-10a The Ductus Deferens and Accessory Glands A posterior view of the urinary bladder and prostate gland, showing subdivisions of the ductus deferens in relation to surrounding structures. Bulbo-urethral glands Urogenital diaphragm Prostatic urethra Prostate gland Ejaculatory duct Duct of seminal gland Ampulla of ductus deferens Seminal gland Ductus deferens Ureter Urinary bladder
  102. 102. © 2012 Pearson Education, Inc. Figure 28-10c The Ductus Deferens and Accessory Glands Histology of the seminal glands. These organs produce most of the volume of seminal fluid. LM × 45Seminal gland Smooth muscle Secretory pockets Lumen
  103. 103. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Prostate Gland • Is a small, muscular organ, about 4 cm (1.6 in.) in diameter • Encircles proximal portion of urethra • Below urinary bladder • Consists of 30–50 compound tubuloalveolar glands • Surrounded by smooth muscle fibers
  104. 104. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Prostatic Fluid • Is slightly acidic • Forms 20%–30% of semen volume • Contains antibiotic seminalplasmin • Is ejected into prostatic urethra • By peristalsis of prostate wall
  105. 105. © 2012 Pearson Education, Inc. Figure 28-10a The Ductus Deferens and Accessory Glands A posterior view of the urinary bladder and prostate gland, showing subdivisions of the ductus deferens in relation to surrounding structures. Bulbo-urethral glands Urogenital diaphragm Prostatic urethra Prostate gland Ejaculatory duct Duct of seminal gland Ampulla of ductus deferens Seminal gland Ductus deferens Ureter Urinary bladder
  106. 106. © 2012 Pearson Education, Inc. Figure 28-10d The Ductus Deferens and Accessory Glands Histological detail of the glands of the prostate. The tissue between the individual glandular units consists largely of smooth muscle. Contractions of this muscle tissue help move the secretions into the ejaculatory duct and urethra. LM × 50Prostate gland Prostatic (tubuloalveolar) glands Connective tissue and smooth muscle
  107. 107. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Bulbo-Urethral Glands (Cowper’s Glands) • Are compound, tubular mucous glands • Round shaped, up to 10 mm (less than 0.5 in.) diameter • Located at base of penis • Covered by fascia of urogenital diaphragm
  108. 108. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Bulbo-Urethral Glands (Cowper’s Glands) • Secrete thick, alkaline mucus • Helps neutralize urinary acids in urethra • Lubricates the glans (penis tip) • Duct of each gland travels alongside penile urethra and empties into urethral lumen
  109. 109. © 2012 Pearson Education, Inc. Figure 28-10a The Ductus Deferens and Accessory Glands A posterior view of the urinary bladder and prostate gland, showing subdivisions of the ductus deferens in relation to surrounding structures. Bulbo-urethral glands Urogenital diaphragm Prostatic urethra Prostate gland Ejaculatory duct Duct of seminal gland Ampulla of ductus deferens Seminal gland Ductus deferens Ureter Urinary bladder
  110. 110. © 2012 Pearson Education, Inc. Figure 28-10e The Ductus Deferens and Accessory Glands Histology of the bulbo-urethral glands, which secrete a thick mucus into the spongy urethra. LM × 175Bulbo-urethral gland Lumen Mucous glands Smooth muscle Capsule
  111. 111. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Semen • Typical ejaculation releases 2–5 mL • Abnormally low volume may indicate problems • With prostate gland or seminal glands • Sperm count • Is taken of semen collected after 36 hours of sexual abstinence • Normal range 20–100 million spermatozoa/mL of ejaculate
  112. 112. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Ejaculate • Is the volume of fluid produced by ejaculation • Contains: • Spermatozoa • Seminal fluid • Enzymes • Including protease, seminalplasmin, prostatic enzyme, and fibrinolysin
  113. 113. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Male External Genitalia • The penis • Is a tubular organ through which distal portion of urethra passes • Conducts urine to exterior • Introduces semen into female’s vagina
  114. 114. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Penis • The root • Is the fixed portion that attaches penis to body wall • Attachment occurs within urogenital triangle, inferior to pubic symphysis • The body (shaft) • Is the tubular, movable portion of the penis • Consists of three cylindrical columns of erectile tissue • The glans • Is the expanded distal end of penis that surrounds external urethral orifice
  115. 115. © 2012 Pearson Education, Inc. Figure 28-11a The Penis A frontal section through the penis and associated organs Prepuce External urethral orifice Glans Spongy urethra Corpus cavernosum Corpus spongiosum Opening from bulbo-urethral gland Bulb of penis Urogenital diaphragm Membranous urethra Prostatic urethra Prostate gland Seminal gland Ureter Trigone of urinary bladder Ductus deferens Opening of ejaculatory duct Bulbo-urethral gland Crus at root of penis
  116. 116. © 2012 Pearson Education, Inc. Figure 28-11b The Penis A sectional view through the penis Dorsal artery (red), veins (blue), and nerve (yellow) Corpora cavernosa Dartos muscle Deep artery of penis Collagenous sheath Spongy urethra Corpus spongiosum
  117. 117. © 2012 Pearson Education, Inc. Figure 28-11c The Penis An anterior and lateral view of the penis, showing positions of the erectile tissues Bulb of penis Membranous urethra Right crus of penis Ischial ramus Corpus spongiosum Corpora cavernosa Scrotum Pubic symphysis Body (shaft) of penis Neck of penis Glans External urethral orifice
  118. 118. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Dermis of the Penis • Contains a layer of smooth muscle • A continuation of dartos muscle • Underlying areolar tissue • Allows skin to move freely • Subcutaneous layer • Contains superficial arteries, veins, and lymphatic vessels
  119. 119. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Prepuce (Foreskin) • Is a fold of skin surrounding tip of penis • Attaches to neck and continues over glans • Preputial glands • In skin of neck and inner surface of prepuce • Secrete waxy material (smegma) that can support bacteria • Circumcision can help prevent infection
  120. 120. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Erectile Tissue • In body of penis • Located deep to areolar tissue • In dense network of elastic fibers • That encircles internal structures of penis • Consists of network of vascular channels • Incompletely separated by partitions of elastic connective tissue and smooth muscle fibers • In resting state: • Arterial branches are constricted • Muscular partitions are tense • Blood flow into erectile tissue is restricted
  121. 121. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Corpora Cavernosa • Two cylindrical masses of erectile tissue • Under anterior surface of flaccid penis • Separated by thin septum • Encircled by dense collagenous sheath • Diverge at their bases, forming the crura of penis • Each crus is bound to ramus of ischium and pubis • By tough connective tissue ligaments • Extend to neck of penis • Erectile tissue surrounds a central artery
  122. 122. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • The Corpus Spongiosum • Relatively slender erectile body that surrounds penile urethra • Extends from urogenital diaphragm to tip of penis and expands to form the glans • Is surrounded by a sheath • With more elastic fibers than corpora cavernosa • Erectile tissue contains a pair of small arteries
  123. 123. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Hormones and Male Reproductive Function • Anterior lobe of the pituitary gland releases: • Follicle-stimulating hormone (FSH) • Luteinizing hormone (LH) • In response to: • Gonadotropin-releasing hormone (GnRH)
  124. 124. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Gonadotropin-Releasing Hormone • Is synthesized in hypothalamus • Carried to pituitary by hypophyseal portal system • Is secreted in pulses • At 60–90 minute intervals • Controls rates of secretion of: • FSH and LH • Testosterone (released in response to LH)
  125. 125. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • FSH and Testosterone • Target nurse cells of seminiferous tubules • Nurse cells • Promote spermatogenesis and spermiogenesis • Secrete androgen-binding protein (ABP)
  126. 126. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Negative Feedback • Spermatogenesis is regulated by: • GnRH, FSH, and inhibin • As spermatogenesis accelerates: • Inhibin secretion increases
  127. 127. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Inhibin • Inhibits FSH production • In anterior lobe of the pituitary gland • Suppresses secretion of GnRH • At hypothalamus
  128. 128. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Inhibin and FSH • Elevated FSH levels • Increase inhibin production • Until FSH returns to normal • If FSH declines: • Inhibin production falls • FSH production increases
  129. 129. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Luteinizing Hormone • Targets interstitial cells of testes • Induces secretion of: • Testosterone • Other androgens
  130. 130. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Testosterone • Is the most important androgen • Stimulates spermatogenesis • Promoting functional maturation of spermatozoa • Affects CNS function • Libido (sexual drive) and related behaviors • Stimulates metabolism • Especially protein synthesis • Blood cell formation • Muscle growth
  131. 131. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Testosterone • Establishes male secondary sex characteristics • Distribution of facial hair • Increased muscle mass and body size • Characteristic adipose tissue deposits • Maintains accessory glands and organs of male reproductive tract
  132. 132. © 2012 Pearson Education, Inc. Figure 28-12 Regulation of Male Reproduction KEY Stimulation Inhibition The hypothalamus secretes the hormone GnRH at a rate and pace that remains relatively steady. FSH targets primarily the nurse cells of the seminiferous tubules. When stimulated by GnRH, the anterior lobe of the pituitary gland releases luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Negative feedback High testosterone levels inhibit the release of GnRH by the hypothalamus. LH targets the interstitial cells of the testes. Inhibin depresses the pituitary production of FSH. Release of Gonadotropin- Releasing Hormone (GnRH) Secretion of Follicle- Stimulating Hormone (FSH) Secretion of Luteinizing Hormone (LH) ANTERIOR LOBE OF THE PITUITARY GLAND HYPOTHALAMUS
  133. 133. © 2012 Pearson Education, Inc. Figure 28-12 Regulation of Male Reproduction KEY Stimulation Inhibition TESTES Interstitial Cell Stimulation Nurse Cell Stimulation Peripheral Effects of Testosterone Testosterone Inhibin Negativefeedback Androgen-binding protein (ABP) binds androgens within the seminiferous tubules which elevates the local concentration of androgens and stimulates the physical maturation of spermatids. Nurse cell environment facilitates both spermatogenesis and spermiogenesis. Maintains libido (sexual drive) and related behaviors Stimulation of bone and muscle growth Establishment and maintenance of male secondary sex characteristics Maintenance of accessory glands and organs of the male reproductive system
  134. 134. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Testosterone • Functions like other steroid hormones • Diffuses across target cell membrane • Binds to intracellular receptor • Hormone–receptor complex • Binds to DNA in nucleus • Circulating in bloodstream • Bound to one of two types of transport proteins • Gonadal steroid-binding globulin (GBG) carries 2/3 of circulating testosterone • Albumins carry 1/3 of testosterone
  135. 135. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Testosterone and Development • Production begins around seventh week of fetal development and reaches prenatal peak after six months • Secretion of Müllerian-inhibiting factor by nurse cells leads to regression of Müllerian ducts • Early surge in testosterone levels stimulates differentiation of male duct system and accessory organs and affects CNS development
  136. 136. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Testosterone and Development • Testosterone programs hypothalamic centers that control: 1. GnRH, FSH, and LH secretion 2. Sexual behaviors 3. Sexual drive
  137. 137. © 2012 Pearson Education, Inc. 28-2 Male Reproductive Functions • Estradiol • Is produced in relatively small amounts (2 ng/dL) • 70% is converted from circulating testosterone • By enzyme aromatase • 30% is secreted by interstitial and nurse cells of testes
  138. 138. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Female Reproductive System • Produces sex hormones and functional gametes • Protects and supports developing embryo • Nourishes newborn infant
  139. 139. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Organs of the Female Reproductive System • Ovaries • Uterine tubes • Uterus • Vagina • External genitalia
  140. 140. © 2012 Pearson Education, Inc. Figure 28-13 The Female Reproductive System Labium majus Labium minus Clitoris Greater vestibular gland Paraurethral glands Urethra Vesicouterine pouch Ovarian follicle Ovary Uterine tube Pubic symphysis Urinary bladder
  141. 141. © 2012 Pearson Education, Inc. Figure 28-13 The Female Reproductive System Myometrium Perimetrium Endometrium Uterus Sigmoid colon Rectouterine pouch Fornix Cervix Vagina Rectum Anus
  142. 142. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Structural Support • Ovaries, uterine tubes, and uterus are enclosed in broad ligament • Uterine tubes • Run along broad ligament • Open into pelvic cavity lateral to ovaries • The mesovarium • Stabilizes position of each ovary
  143. 143. © 2012 Pearson Education, Inc. Figure 28-14a The Ovaries and Their Relationships to the Uterine Tube and Uterus A posterior view of the uterus, uterine tubes, and ovaries Vaginal wall Uterosacral ligament Ureter Ovary Infundibulum Suspensory ligament Ovarian artery and vein Fimbriae Uterine tube Ovarian ligament Uterus Vaginal rugae Cervix External os
  144. 144. © 2012 Pearson Education, Inc. Figure 28-14a The Ovaries and Their Relationships to the Uterine Tube and Uterus A posterior view of the uterus, uterine tubes, and ovaries Broad ligament Uterus Mesovarium Suspensory ligament Retractor
  145. 145. © 2012 Pearson Education, Inc. Figure 28-14b The Ovaries and Their Relationships to the Uterine Tube and Uterus A sectional view of the ovary, uterine tube, and associated mesenteries Uterine tube Medulla Corpus luteum Cortex Tunica albuginea Mature follicle Germinal epithelium Egg nest Broad ligament Mesovarium Ovarian hilum Mesosalpinx
  146. 146. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Ovaries • Are small, almond-shaped organs near lateral walls of pelvic cavity • Three main functions 1. Production of immature female gametes (oocytes) 2. Secretion of female sex hormones (estrogens, progestins) 3. Secretion of inhibin, involved in feedback control of pituitary FSH
  147. 147. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Ovary Support • Mesovarium • Ovarian ligament extends from uterus to ovary • Suspensory ligament extends from ovary to pelvic wall • Contains the ovarian artery and ovarian vein • These vessels connect to ovary at ovarian hilum, where ovary attaches to mesovarium
  148. 148. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Visceral Peritoneum of the Ovary • Also called germinal epithelium • Covers surface of ovary • Consists of columnar epithelial cells • Overlies tunica albuginea
  149. 149. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Stroma • Are interior tissues of ovary • Superficial cortex • Deeper medulla • Gametes are produced in cortex
  150. 150. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Oogenesis • Also called ovum production • Begins before birth • Accelerates at puberty • Ends at menopause
  151. 151. © 2012 Pearson Education, Inc. Figure 28-15 Oogenesis Oogenesis Mitosis of oogonium Oogonium Oogonium Primary oocyte (diploid) Unlike spermatogonia, the oogonia (o-o-GO-ne-uh), or female reproductive stem cells, complete their mitotic divisions before birth.
  152. 152. © 2012 Pearson Education, Inc. Figure 28-15 Oogenesis Meiosis I Secondary oocyte (diploid) DNA replication Primary oocyte Tetrad First polar body First polar body may not complete meiosis II Between the third and seventh months of fetal development, the daughter cells, or primary oocytes (O-o-sıts), prepare to undergo meiosis. They proceed as far as the prophase of meiosis I, but then the process comes to a halt. The primary oocytes remain in a state of suspended development until the individual reaches puberty, when rising levels of FSH trigger the start of the ovarian cycle. Each month after the ovarian cycle begins, some of the primary oocytes are stimulated to undergo further development. Meiosis I is then completed, yielding a secondary oocyte and a polar body. Oogenesis
  153. 153. © 2012 Pearson Education, Inc. Figure 28-15 Oogenesis Meiosis II Secondary oocyte released in metaphase of meiosis II Second polar body Mature ovum (haploid Each month after the ovarian cycle begins, one or more secondary oocytes leave the ovary suspended in metaphase of meiosis II. Meiosis II will be completed only if fertilization occurs. The polar body produced in meiosis I may or may not undergo meiosis II; in either case, the polar bodies soon degenerate. Oogenesis
  154. 154. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Fetal Development • Between third and seventh months: • Primary oocytes prepare for meiosis • Stop at prophase of meiosis I • Atresia • Is the degeneration of primordial follicles • Ovaries have about 2 million primordial follicles at birth • Each containing a primary oocyte • By puberty: • Number drops to about 400,000
  155. 155. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Process of Oogenesis • Primary oocytes remain in suspended development until puberty • At puberty: • Rising FSH triggers start of ovarian cycle • Each month thereafter: • Some primary oocytes are stimulated to develop further
  156. 156. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Oogenesis: Two Characteristics of Meiosis 1. Cytoplasm of primary oocyte divides unevenly • Producing one ovum (with original cytoplasm) • And two or three polar bodies (that disintegrate) 1. Ovary releases secondary oocyte (not mature ovum) • Suspended in metaphase of meiosis II • Meiosis is completed upon fertilization
  157. 157. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Ovarian Cycle • After sexual maturation • A different group of primordial follicles is activated each month • Is divided into: • Follicular phase (preovulatory phase) • Luteal phase (postovulatory phase)
  158. 158. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Ovarian Cycle • Ovarian Follicles • Are specialized structures in cortex of ovaries • Where oocyte growth and meiosis I occur • Primary oocytes • Are located in outer part of ovarian cortex • Near tunica albuginea • In clusters called egg nests
  159. 159. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Primordial Follicle • Each primary oocyte in an egg nest • Is surrounded by follicle cells • Primary oocyte and follicle cells form a primordial follicle
  160. 160. © 2012 Pearson Education, Inc. Figure 28-16 The Ovarian Cycle (Step 1) Primordial follicles in egg nest LM × 1440 Primary oocyte Follicle cells
  161. 161. © 2012 Pearson Education, Inc. Figure 28-16 The Ovarian Cycle (Step 2) Formation of primary follicle LM × 1092 Granulosa cells Thecal cells Primary oocytes Zona pellucida
  162. 162. © 2012 Pearson Education, Inc. Figure 28-16 The Ovarian Cycle (Step 3) Formation of secondary follicle LM × 1052 Zona pellucida Granulosa cells Nucleus of primary oocyte Thecal cells
  163. 163. © 2012 Pearson Education, Inc. Figure 28-16 The Ovarian Cycle (Step 4) Formation of tertiary follicle LM × 136 Granulosa cells Antrum containing follicular fluid Corona radiata Secondary oocyte
  164. 164. © 2012 Pearson Education, Inc. Figure 28-16 The Ovarian Cycle (Step 5) Ovulation Follicular fluid Secondary oocyte within corona radiata Ruptured follicle wall Outer surface of ovary Primordial follicles Primary follicle Secondary follicle Tertiary follicle Released secondary oocyte Corpus albicans Corpus luteum Corona radiata
  165. 165. © 2012 Pearson Education, Inc. Figure 28-16 The Ovarian Cycle (Step 6) Formation of corpus luteum LM × 208
  166. 166. © 2012 Pearson Education, Inc. Figure 28-16 The Ovarian Cycle (Step 7) Formation of corpus albicans LM × 208
  167. 167. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Uterine Tubes • Also called Fallopian tubes or oviducts • Are hollow, muscular tubes about 13 cm (5.2 in.) long • Transport oocyte from ovary to uterus
  168. 168. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Three Segments of the Uterine Tubes 1. Infundibulum • An expanded funnel near ovary • With fimbriae that extend into pelvic cavity • Inner surfaces lined with cilia that beat toward middle segment 1. Ampulla • Middle segment • Smooth muscle layers in wall become thicker approaching uterus 1. Isthmus • A short segment between ampulla and uterine wall
  169. 169. © 2012 Pearson Education, Inc. Figure 28-17a The Uterine Tubes Regions of the uterine tubes, posterior view Uterus Isthmus Ampulla Infundibulum Fimbriae
  170. 170. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Histology of the Uterine Tube • Epithelium lining uterine tube • Contains scattered mucin-secreting cells • Mucosa is surrounded by concentric layers of smooth muscle
  171. 171. © 2012 Pearson Education, Inc. Figure 28-17b The Uterine Tubes A sectional view of the isthmus Columnar epithelium Lamina propria Smooth muscle Isthmus LM × 122
  172. 172. © 2012 Pearson Education, Inc. Figure 28-17c The Uterine Tubes A colorized SEM of the ciliated lining of the uterine tube Epithelial surface Cilia Microvilli of mucin- secreting cells SEM × 4000
  173. 173. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Uterine Tube and Oocyte Transport • Involves ciliary movement and peristaltic contractions in walls of uterine tube • A few hours before ovulation, nerves from hypogastric plexus: • “Turn on” beating pattern • Initiate peristalsis • From infundibulum to uterine cavity • Normally takes 3–4 days
  174. 174. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Uterine Tube and Fertilization • For fertilization to occur: • Secondary oocyte must meet spermatozoa during first 12–24 hours • Fertilization typically occurs: • Near boundary between ampulla and isthmus • Uterine tube provides nutrient-rich environment by secretions from peg cells • Containing lipids and glycogen • Nutrients supply spermatozoa and developing pre- embryo
  175. 175. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Uterus • Provides for developing embryo (weeks 1–8) and fetus (week 9 through delivery) • Mechanical protection • Nutritional support • Waste removal
  176. 176. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Uterus • Is pear-shaped • 7.5 cm long, 5 cm diameter (3 in. × 2 in.) • Weighs 30–40 g (1–1.4 oz) • Normally bends anteriorly near base (anteflexion) • In retroflexion, uterus bends backward
  177. 177. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Suspensory Ligaments of Uterus • Uterosacral ligaments • Prevent inferior–anterior movement • Round ligaments • Restrict posterior movement • Cardinal (lateral) ligaments • Prevent inferior movement
  178. 178. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Uterine Body • Is largest portion of uterus • Ends at isthmus • Fundus • Is rounded portion of uterine body • Superior to attachment of uterine tubes
  179. 179. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Cervix • Is inferior portion of uterus • Extends from isthmus to vagina • Distal end projects about 1.25 cm (0.5 in.) into vagina • External os • Also called external orifice of uterus • Is surrounded by distal end of cervix • Leads into cervical canal
  180. 180. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Cervical Canal • Is a constricted passageway opening to uterine cavity of body • At internal os (internal orifice)
  181. 181. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Blood Supply of the Uterus • Branches of uterine arteries • Arising from branches of internal iliac arteries • Ovarian arteries • Arising from abdominal aorta • Veins and lymphatic vessels
  182. 182. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Nerves of the Uterus • Autonomic fibers from hypogastric plexus (sympathetic) • Sacral segments S3 and S4 (parasympathetic) • Segmental blocks • Anesthetic procedure used during labor • Target spinal nerves T10–L1
  183. 183. © 2012 Pearson Education, Inc. Figure 28-18a The Uterus A posterior view with the left portion of the uterus, left uterine tube, and left ovary shown in section Vaginal rugae See Figure 28–21 External os of uterus Vaginal artery Cervical canal Isthmus of uterus Internal os of uterus Uterine artery and vein See Figure 28–19 Myometrium Fimbriae Infundibulum Ampulla Isthmus Uterine cavity Vagina Endometrium Perimetrium
  184. 184. © 2012 Pearson Education, Inc. Figure 28-18a The Uterus A posterior view with the left portion of the uterus, left uterine tube, and left ovary shown in section Cervix Uterine cavity Body of uterus Fundus of uterus Uterine tube Ovary Broad ligament Round ligament of uterus Ovarian ligament Mesovarium Ovarian artery and vein Suspensory ligament of ovary Vagina
  185. 185. © 2012 Pearson Education, Inc. Figure 28-18b The Uterus A superior view of the ligaments that stabilize the position of the uterus in the pelvic cavity ANTERIOR POSTERIOR Uterus Ovary Cardinal ligaments (under broad ligament) Uterosacral ligament Sigmoid colon Broad ligament Suspensory ligament of ovary Uterine tube Ovarian ligament Round ligament of uterus Urinary bladder
  186. 186. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Uterine Wall • Has a thick, outer, muscular myometrium • Has a thin, inner, glandular endometrium (mucosa) • The perimetrium • Is an incomplete serous membrane • Continuous with peritoneal lining • Covers fundus and posterior surface of uterine body and isthmus
  187. 187. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Myometrium • The thickest portion of the uterine wall • Constitutes almost 90% of the mass of the uterus • Arranged into longitudinal, circular, and oblique layers • Provides force to move fetus out of uterus into vagina
  188. 188. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Endometrium • Contributes about 10% of uterine mass • Glandular and vascular tissues support physiological demands of growing fetus • Uterine glands • Open onto endometrial surface • Extend deep into lamina propria • Estrogen • Causes uterine glands, blood vessels, and epithelium to change with phases of monthly uterine cycle
  189. 189. © 2012 Pearson Education, Inc. Figure 28-19a The Uterine Wall A diagrammatic sectional view of the uterine wall, showing the endometrial regions and the circulatory supply to the endometrium Uterine artery Radial artery Arcuate arteries Spiral artery Uterine cavity Uterine glands Endometrium Myometrium Perimetrium Straight artery
  190. 190. © 2012 Pearson Education, Inc. Figure 28-19b The Uterine Wall The basic histological structure of the uterine wall Uterine wall LM × 32 Uterine cavity Endometrium Myometrium Simple columnar epithelium Uterine glands Functional zone Basilar zone
  191. 191. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Two Divisions of Endometrium 1. The functional zone • Contains most of the uterine glands • Contributes most of endometrial thickness • Undergoes dramatic changes in thickness and structure during menstrual cycle 1. The basilar zone • Attaches endometrium to myometrium • Contains terminal branches of tubular endometrial glands
  192. 192. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Blood Supply of Endometrium • Arcuate arteries • Encircle endometrium • Radial arteries • Supply straight arteries (to basilar zone) • Supply spiral arteries (to functional zone)
  193. 193. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Cyclical Changes in Endometrium • Basilar zone remains relatively constant • Functional zone undergoes cyclical changes • In response to sex hormone levels • Produce characteristic features of uterine cycle
  194. 194. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Uterine Cycle (Menstrual Cycle) • Is a repeating series of changes in endometrium • Lasts from 21 to 35 days • Average 28 days • Responds to hormones of ovarian cycle • Menses and proliferative phase • Occur during ovarian follicular phase • Secretory phase • Occurs during ovarian luteal phase
  195. 195. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Menses • Is the degeneration of functional zone • Occurs in patches • Is caused by constriction of spiral arteries • Reducing blood flow, oxygen, and nutrients • Weakened arterial walls rupture • Releasing blood into connective tissues of functional zone
  196. 196. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Menses • Degenerating tissues break away, enter uterine lumen • Entire functional zone is lost • Through external os and vagina • Only functional zone is affected • Deeper, basilar zone is supplied by straight arteries
  197. 197. © 2012 Pearson Education, Inc. Figure 28-20a The Appearance of the Endometrium during the Uterine Cycle Myometrium Endometrium Perimetrium Cervix The appearance of the endometrium at menses MYOMETRIUM LM × 63Menses Uterine cavityUterine glands Basilar zone of endometrium
  198. 198. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Menstruation • Is the process of endometrial sloughing • Lasts 1–7 days • Sheds 35–50 mL (1.2–1.7 oz) blood
  199. 199. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Proliferative Phase • Epithelial cells of uterine glands • Multiply and spread across endometrial surface • Restore integrity of uterine epithelium • Further growth and vascularization • Completely restores functional zone • Occurs at same time as: • Enlargement of primary and secondary follicles in ovary
  200. 200. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Proliferative Phase • Is stimulated and sustained by: • Estrogens secreted by developing ovarian follicles • Entire functional zone is highly vascularized • Small arteries • Spiral toward inner surface • From larger arteries in myometrium
  201. 201. © 2012 Pearson Education, Inc. Figure 28-20b The Appearance of the Endometrium during the Uterine Cycle Uterine cavity Myometrium The appearance of the endometrium during the proliferative phase ENDOMETRIUM MYOMETRIUM LM × 66 Basilar zone Functional zone Uterine cavityUterine glands Proliferative phase
  202. 202. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Secretory Phase • Endometrial glands enlarge, increasing rate of secretion • Arteries of uterine wall • Elongate and spiral through functional zone • Begins at ovulation and persists as long as corpus luteum remains intact • Peaks about 12 days after ovulation • Glandular activity declines • Generally lasts 14 days • Ends as corpus luteum stops producing stimulatory hormones
  203. 203. © 2012 Pearson Education, Inc. Figure 28-20c The Appearance of the Endometrium during the Uterine Cycle The appearance of the endometrium during the secretory phase of the uterine cycle LM × 52 Functional zone Secretory phase Uterine cavity LM × 150Detail of uterine glands Uterine glands
  204. 204. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Menarche • The first uterine cycle • Begins at puberty (age 11–12) • Menopause • The termination of uterine cycles • Age 45–55
  205. 205. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Amenorrhea • Primary amenorrhea • Failure to initiate menses • Transient secondary amenorrhea • Interruption of 6 months or more • Caused by physical or emotional stresses
  206. 206. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Vagina • Is an elastic, muscular tube • Extends between cervix and vestibule • 7.5–9 cm (3–3.6 in.) long • Highly distensible
  207. 207. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Vagina • Cervix projects into vaginal canal • Fornix is shallow recess surrounding cervical protrusion • Lies parallel to: • Rectum, posteriorly • Urethra, anteriorly
  208. 208. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Blood Supply of the Vagina • Is through vaginal branches of internal iliac (uterine) arteries and veins • Innervation of the Vagina • Hypogastric plexus • Sacral nerves • Branches of pudendal nerve
  209. 209. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Three Functions of the Vagina 1. Passageway for elimination of menstrual fluids 2. Receives spermatozoa during sexual intercourse 3. Forms inferior portion of birth canal
  210. 210. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Anatomy and Histology of the Vagina • The Vaginal Wall • Contains a network of blood vessels and layers of smooth muscle • Is moistened by: • Secretions of cervical glands • Water movement across permeable epithelium
  211. 211. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Hymen • Is an elastic epithelial fold • That partially blocks entrance to vagina • Usually ruptured by sexual intercourse or tampon usage
  212. 212. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Vaginal Muscles • Two bulbospongiosus muscles extend along either side of vaginal entrance • Vestibular bulbs • Masses of erectile tissue that lie beneath the muscles • Have same embryological origins as corpus spongiosum of penis
  213. 213. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Vaginal Epithelium • Is nonkeratinized, stratified, and squamous • Forms folds (rugae) • Changes with ovarian cycle • Vaginal Lamina Propria • Is thick and elastic • Contains small blood vessels, nerves, and lymph nodes
  214. 214. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Vaginal Mucosa • Is surrounded by elastic muscularis layer • Layers of smooth muscle fibers • Arranged in circular and longitudinal bundles • Continuous with uterine myometrium
  215. 215. © 2012 Pearson Education, Inc. Figure 28-21a The Histology of the Vagina Fornix Vaginal artery Vaginal vein Rugae Hymen VestibuleLabia minora Greater vestibular gland Vaginal canal
  216. 216. © 2012 Pearson Education, Inc. Figure 28-21b The Histology of the Vagina LM × 25The vaginal wall Bundles of smooth muscle fibers Blood vessels Lamina propria Stratified squamous epithelium (nonkeratinized) Lumen of vaginal canal
  217. 217. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Vaginal Bacteria • A population of harmless resident bacteria • Supported by nutrients in cervical mucus • Creates acidic environment • Restricts growth of many pathogens • A Vaginal Smear • Is a sample of epithelial cells shed at surface of vagina • Used to estimate stage in ovarian and uterine cycles
  218. 218. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The External Genitalia • Vulva (or pudendum) • Area containing female external genitalia • Vestibule • A central space bounded by small folds (labia minora) • Covered with smooth, hairless skin • Urethra opens into vestibule • Anterior to vaginal entrance
  219. 219. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Paraurethral Glands • Also called Skene’s glands • Discharge into urethra near external opening • The Clitoris • A small protuberance in vestibule • Has same embryonic structures as penis • Extensions of labia minora form prepuce or hood
  220. 220. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Vestibular Glands • Lesser vestibular glands • Secrete onto exposed surface of vestibule • Greater vestibular glands (or Bartholin’s glands) • Secrete into vestibule near vaginal entrance
  221. 221. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Mons Pubis and Labia Majora • Form outer limits of vulva • Protect and cover inner structures • Contain adipose tissue • Sebaceous glands and apocrine sweat glands • Secrete onto inner surface of labia majora
  222. 222. © 2012 Pearson Education, Inc. Figure 28-22 The Female External Genitalia Mons pubis Labia minora Hymen (torn) Vaginal entrance Labia majora Anus Prepuce of clitoris Glans of clitoris Urethral opening Vestibule Vestibular bulb Greater vestibular gland
  223. 223. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Mammary Glands • Secrete milk to nourish an infant (lactation) • Are specialized organs of integumentary system • Are controlled by hormones of reproductive system and the placenta • Lie in pectoral fat pads deep to skin of chest • Nipple on each breast • Contains ducts from mammary glands to surface • Areola • Reddish-brown skin around each nipple
  224. 224. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Mammary Glands • Consist of lobes • Each containing several secretory lobules • Separated by dense connective tissue
  225. 225. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Suspensory Ligaments of the Breast • Bands of connective tissue • Originate in dermis of overlying skin • Areolar tissue separates mammary gland complex from underlying pectoralis muscles • Blood Supply of Mammary Glands • Branches of internal thoracic artery
  226. 226. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Mammary Gland Ducts • Leave lobules • Converge • Form single lactiferous duct in each lobe • Lactiferous Duct • Enlarges • Forms expanded chamber (lactiferous sinus) • 15–20 lactiferous sinuses open to each nipple
  227. 227. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • An Active Mammary Gland • Is a tubuloalveolar gland • Consisting of multiple glandular tubes • Ending in secretory alveoli • Does not complete development unless pregnancy occurs
  228. 228. © 2012 Pearson Education, Inc. Figure 28-23a The Mammary Glands The mammary glands of the left breast Pectoral fat pad Pectoralis major muscle Suspensory ligaments Lobules of two lobes of the mammary glands Lactiferous duct Areola Nipple Lactiferous sinus
  229. 229. © 2012 Pearson Education, Inc. Figure 28-23b The Mammary Glands An inactive mammary gland of a nonpregnant woman LM × 100Resting mammary gland Connective tissue Lactiferous duct Secretory alveoli
  230. 230. © 2012 Pearson Education, Inc. Figure 28-23c The Mammary Glands An active mammary gland of a nursing woman LM × 131Active mammary gland Secretory alveoli Lactiferous duct Milk
  231. 231. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Hormones and the Female Reproductive Cycle • Involve secretions of pituitary gland and gonads • Form a complex pattern that coordinates ovarian and uterine cycles • Circulating hormones • Control female reproductive cycle • Coordinate ovulation and uterus preparation
  232. 232. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Hormones and the Female Reproductive Cycle • GnRH from the hypothalamus regulates reproductive function • GnRH pulse frequency and amplitude change over course of ovarian cycle • Changes in GnRH pulse frequency are controlled by: • Estrogens that increase pulse frequency • Progestins that decrease pulse frequency
  233. 233. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • The Endocrine Cells • Of anterior lobe of the pituitary • Each group of endocrine cells: • Responds to different GnRH pulse frequencies • Is sensitive to some frequencies, insensitive to others
  234. 234. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Hormones and the Follicular Phase • Begins with FSH stimulation • Monthly • Some primordial follicles develop into primary follicles • As follicles enlarge: • Thecal cells produce androstenedione
  235. 235. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Androstenedione • Is a steroid hormone • Is an intermediate in synthesis of estrogens and androgens • Is absorbed by granulosa cells and converted to estrogens
  236. 236. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Interstitial Cells • Scattered throughout ovarian stroma • Also secrete small amounts of estrogens • Circulating estrogens • Are bound primarily to albumins • Lesser amounts carried by gonadal steroid-binding globulin (GBG) • Three types: estradiol, estrone, and estriol
  237. 237. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Estradiol • Is most abundant • Has most pronounced effects on target tissues • Is dominant hormone prior to ovulation
  238. 238. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Estrogen Synthesis • Androstenedione is converted to testosterone • Enzyme aromatase converts testosterone to estradiol • Estrone and estriol are synthesized from androstenedione
  239. 239. © 2012 Pearson Education, Inc. Figure 28-24 Pathways of Steroid Hormone Synthesis in Males and Females = Common pathways = Primary pathways in females = Primary pathways in males KEY DihydrotestosteroneTestosterone Aromatase Estrone Estriol In some tissues Aromatase Progesterone Progestins Cholesterol Androstenedione Androgens Estradiol Other Estrogens
  240. 240. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Five Functions of Estrogen 1. Stimulates bone and muscle growth 2. Maintains female secondary sex characteristics • Such as body hair distribution and adipose tissue deposits 1. Affects central nervous system (CNS) activity • Especially in the hypothalamus, where estrogens increase the sexual drive 1. Maintains functional accessory reproductive glands and organs 2. Initiates repair and growth of endometrium
  241. 241. © 2012 Pearson Education, Inc. Figure 28-25 Regulation of Female Reproduction HYPOTHALAMUS ANTERIOR LOBE OF PITUITARY GLAND Luteal Phase of the Ovarian Cycle Follicular Phase of the Ovarian Cycle Release of Gonadotropin- Releasing Hormone (GnRH) Release of GnRH Production and secretion of FSH Production of LH Secretion of LH Negative feedback 2 3 1
  242. 242. © 2012 Pearson Education, Inc. Figure 28-25 Regulation of Female Reproduction KEY Stimulation Inhibition Effects on CNS Stimulation of bone and muscle growth Establishment and maintenance of female secondary sex characteristics Maintenance of accessory glands and organs Stimulation of endometrial growth and secretion Luteal Phase of the Ovarian Cycle Follicular Phase of the Ovarian Cycle OVARY After day 10 Before day 10 • Follicle development • Secretion of inhibin • Secretion of estrogens • Meiosis I completion • Ovulation • Corpus luteum formation Secretion of progesterone
  243. 243. © 2012 Pearson Education, Inc. Figure 28-25 Regulation of Female Reproduction FOLLICULAR PHASE OF OVARIAN CYCLE LUTEAL PHASE OF OVARIAN CYCLE Gonadotropic hormone levels (IU/L) Follicle stages during the ovarian cycle DAYS Follicle development Ovulation Corpus luteum formation Mature corpus luteum Corpus albicans FSH LH GnRH pulse frequency (pulses/day) Ovarian hormone levels Progesterone Inhibin Estrogens
  244. 244. © 2012 Pearson Education, Inc. Figure 28-25 Regulation of Female Reproduction FOLLICULAR PHASE OF OVARIAN CYCLE LUTEAL PHASE OF OVARIAN CYCLE DAYS Endometrial changes during the uterine cycle Phases of the uterine cycle Basal body temperature (°C) MENSES PROLIFERATIVE PHASE SECRETORY PHASE Destruction of functional zone Repair and regeneration of functional zone Secretion by uterine glands
  245. 245. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Summary: Hormonal Regulation of the Female Reproductive Cycle • Early in follicular phase of ovarian cycle • Estrogen levels are low • GnRH pulse frequency is 16–24/day (1 per 60–90 minutes) • As tertiary follicles form, concentration of circulating estrogens rises steeply • And GnRH pulse frequency increases to 36/day (1 per 30–60 minutes)
  246. 246. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Summary: Hormonal Regulation of the Female Reproductive Cycle • In follicular phase • Switchover occurs • When estrogen levels exceed threshold value for about 36 hours • Resulting in massive release of LH from the anterior lobe of the pituitary gland
  247. 247. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Summary: Hormonal Regulation of the Female Reproductive Cycle • In follicular phase • Sudden surge in LH concentration triggers: 1. Completion of meiosis I by primary oocyte 2. Rupture of follicular wall 3. Ovulation • Ovulation occurs 34–38 hrs after LH surge begins (9 hrs after LH peak)
  248. 248. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Summary: Hormonal Regulation of the Female Reproductive Cycle • In luteal phase of ovarian cycle • High LH levels trigger ovulation • Promote progesterone secretion • Trigger formation of corpus luteum • Frequency of GnRH pulses stimulates LH more than FSH • LH maintains structure and secretory function of corpus luteum
  249. 249. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Summary: Hormonal Regulation of the Female Reproductive Cycle • Luteal phase • Progesterone levels remain high for one week • Unless pregnancy occurs, corpus luteum begins to degenerate • Progesterone and estrogen levels drop • GnRH pulse frequency increases • Stimulating FSH secretion • Ovarian cycle begins again
  250. 250. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Hormones and the Uterine Cycle • Corpus luteum degenerates • Progesterone and estrogen levels decline • Resulting in menses • Endometrial tissue sheds several days • Until rising estrogen stimulates regeneration of functional zone
  251. 251. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Hormones and the Uterine Cycle • Proliferative phase continues • Until rising progesterone starts secretory phase • Increase in estrogen and progesterone • Causes enlargement of endometrial glands • And increase in secretory activities
  252. 252. © 2012 Pearson Education, Inc. 28-3 The Female Reproductive System • Hormones and Body Temperature • Monthly hormonal fluctuations affect core body temperature • During luteal phase progesterone dominates • During follicular phase estrogen dominates and basal body temperature decreases about 0.3°C • Upon ovulation basal body temperature (BBT) declines noticeably • Day after ovulation temperature rises
  253. 253. © 2012 Pearson Education, Inc. 28-4 Sexual Function • Autonomic Function Controls the Reproductive System • Coitus (Copulation) • Sexual intercourse • Introduces semen into female reproductive tract
  254. 254. © 2012 Pearson Education, Inc. 28-4 Sexual Function • Male Sexual Function • Is coordinated by complex neural reflexes • Using sympathetic and parasympathetic divisions of ANS • Male sexual arousal • Leads to increase in parasympathetic outflow over pelvic nerves, which leads to erection
  255. 255. © 2012 Pearson Education, Inc. 28-4 Sexual Function • Male Sexual Stimulation • Initiates secretion of bulbo-urethral glands • Lubricates penile urethra and surface of glans • Leads to coordinated processes of emission and ejaculation
  256. 256. © 2012 Pearson Education, Inc. 28-4 Sexual Function • Emission • Occurs under sympathetic stimulation • Peristaltic contractions of ampulla • Push fluid and spermatozoa into prostatic urethra • Seminal glands contract • Increasing in force and duration • Peristaltic contractions in prostate gland • Move seminal mixture into urethra • Sympathetic contraction of urinary bladder and internal urethral sphincter • Prevents passage of semen into bladder
  257. 257. © 2012 Pearson Education, Inc. 28-4 Sexual Function • Ejaculation • Occurs as powerful, rhythmic contractions • In ischiocavernosus and bulbospongiosus muscles • That stiffen penis • Push semen toward external urethral opening • Causes pleasurable sensations (orgasm) • Followed by subsidence of erectile tissue (detumescence)
  258. 258. © 2012 Pearson Education, Inc. 28-4 Sexual Function • Impotence • Also called male sexual dysfunction • Is an inability to achieve or maintain an erection • Caused by physical or psychological factors
  259. 259. © 2012 Pearson Education, Inc. 28-4 Sexual Function • Female Sexual Function • Parasympathetic activation leads to: • Engorgement of erectile tissues • Increased secretion of cervical mucous glands and greater vestibular glands • Blood vessels in vaginal walls fill with blood • Fluid moves from underlying connective tissues • To vaginal surfaces
  260. 260. © 2012 Pearson Education, Inc. 28-4 Sexual Function • Female Orgasm • Is accompanied by: • Peristaltic contractions of uterine and vaginal walls • Rhythmic contractions of bulbospongiosus and ischiocavernosus muscles
  261. 261. © 2012 Pearson Education, Inc. 28-4 Sexual Function • Sexually Transmitted Diseases (STDs) • Are transferred by sexual intercourse • Include bacterial, viral, and fungal infections • Pelvic inflammatory disease (PID) • AIDS • Gonorrhea • Syphilis • Herpes • Genital warts • Chancroid
  262. 262. © 2012 Pearson Education, Inc. 28-5 Effects of Aging on the Reproductive System • Effects of Aging • Female reproductive system • Changes associated with menopause • Male reproductive system • Changes associated with male climacteric (andropause) • Occur gradually, over longer time period
  263. 263. © 2012 Pearson Education, Inc. 28-5 Effects of Aging on the Reproductive System • Menopause • Is the time that ovulation and menstruation cease • Typically occurs around age 45–55 • Circulating concentrations of estrogens and progesterone decline • Production of GnRH, FSH, and LH rises sharply
  264. 264. © 2012 Pearson Education, Inc. 28-5 Effects of Aging on the Reproductive System • Perimenopause • The interval immediately preceding menopause • Ovarian and uterine cycles become irregular • Due to shortage of primordial follicles • Estrogen levels decline • Ovulation is not triggered
  265. 265. © 2012 Pearson Education, Inc. 28-5 Effects of Aging on the Reproductive System • Decline in Estrogen Levels • Leads to: • Reduction in uterus and breast size • Thinning of urethral and vaginal epithelia • Reduction in bone deposition (osteoporosis)
  266. 266. © 2012 Pearson Education, Inc. 28-5 Effects of Aging on the Reproductive System • The Male Climacteric (Andropause) • Is the period of declining reproductive function • Circulating testosterone begins to decline • Between ages 50 and 60 • Circulating FSH and LH increase • Sperm production continues • Sexual activity gradually decreases • With declining testosterone levels
  267. 267. © 2012 Pearson Education, Inc. 28-6 Sex Hormones and Homeostasis • Males • Sperm count must be adequate • Semen must have correct pH and nutrients • Erection and ejaculation must function properly
  268. 268. © 2012 Pearson Education, Inc. 28-6 Sex Hormones and Homeostasis • Females • Ovarian and uterine cycles must coordinate properly • Ovulation and oocyte transport must occur normally • Environment of reproductive tract must support • Survival and movement of sperm • Fertilization of oocyte
  269. 269. © 2012 Pearson Education, Inc. Table 28-1 Hormones of the Reproductive System
  270. 270. © 2012 Pearson Education, Inc. 28-6 Reproductive System Integration • Human Reproduction • Requires normal function of multiple systems • Reproductive system • Digestive system • Endocrine system • Nervous system • Cardiovascular system • Urinary system
  271. 271. © 2012 Pearson Education, Inc. Figure 28-26 System Integrator: The Reproductive System Body System Body System S Y S T E M I N T E G R A T O R Reproductive SystemReproductive System CardiovascularRespiratoryLymphaticEndocrineNervousMuscularSkeletalIntegumentaryDigestiveUrinary CardiovascularRespiratoryLymphaticEndocrineNervousMuscularSkeletalIntegumentary Page857Page807Page759Page632Page543Page369Page275Page165 Digestive Page910 Urinary Page992 The Male Reproductive System For all systems, the reproductive system secretes hormones with effects on growth and metabolism. Accessory organ secretions may have antibacterial action that helps prevent urethral infections in males Figure 28-26 diagrams the functional relationships between the reproductive system and the other body systems. In pregnant women, digestive organs are crowded by developing fetus, constipation is common, and appetite increases Changes in respiratory rate and depth occur during sexual arousal, under control of the nervous system Lysozymes and bactericidal chemicals in secretions provide innate defense against reproductive tract infections Estrogens may help maintain healthy vessels and slow development of atherosclerosis Steroid sex hormones and inhibin inhibit secretory activities of hypothalamus and pituitary gland Sex hormones affect CNS development and sexual behaviors Reproductive hormones, especially testosterone, accelerate skeletal muscle growth Sex hormones stimulate growth and maintenance of bones; sex hormones at puberty accelerate growth and closure of epiphyseal cartilages Reproductive hormones affect distribution of body hair and subcutaneous fat deposits Covers external genitalia; provides sensations that stimulate sexual behaviors; mammary gland secretions provide nourishment for newborn Pelvis protects reproductive organs of females, portion of ductus deferens and accessory glands in males Contractions of skeletal muscles eject semen from male reproductive tract; muscle contractions during sexual act produce pleasurable sensations in both sexes Controls sexual behaviors and sexual function Hypothalamic regulatory hormones and pituitary hormones regulate sexual development and function; oxytocin stimulates smooth muscle contractions in uterus and mammary glands Distributes reproductive hormones; provides nutrients, oxygen, and waste removal for fetus; local blood pressure changes responsible for physical changes during sexual arousal Provides IgA for secretions by epithelial glands; assists in repairs and defense against infection Provides oxygen and removes carbon dioxide generated by tissues of reproductive system Provides additional nutrients required to support gamete production and (in pregnant women) embryonic and fetal development Urethra in males carries semen to exterior; kidneys remove wastes generated by reproductive tissues and (in pregnant women) by a growing emtryo and fetus The REPRODUCTIVE System

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