The reproductive system ppt


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The reproductive system ppt

  1. 1. The Reproductive System Samantha Blum
  2. 2. Male Reproductive SystemThis system has four major divisions: the testis, the genital ducts, the auxillary glands, and the penis.
  3. 3. The Testis• These paired glands (plural = testes) are mixed exocrine and endocrine glands.
  4. 4. Scrotum• The testes are suspended within the scrotum, which is, in part, an extension of the abdominal body wall lined by serosa internally and covered externally by integument. No slide is available.Integument• This has a stratified squamous epithelium with large sebaceous and sweat glands.Dartos muscle (smooth muscle)Tunica vaginalis (parietal layer of serosa)• The parietal layer of this serosa adheres to the inner aspect of the scrotal wall; it is reflected onto the external surface of the testis as the visceral layer (see below).
  5. 5. Structure of the TestisSeminiferous tubules (schematic). These are the sites of spermatogenesis. The stratified epithelium contains two cell types, Sertoli cells and spermatogenic cells (schematic). External to the seminiferous tubule epithelium is a basement membrane and lamina propria. Smooth muscle-like cells (myoid cells, peritubular cells) also surround the tubule.1. Sertoli cells (sustentacular cells). These are supporting, non-spermatogenic cells.• Identify Sertoli cells (50X, 100X, 100X, 100X). The cytoplasmic outline of these large cells is often difficult to discern, but their nuclei are characteristically large and oval, with a prominent round nucleolus (best seen in slide E-27).
  6. 6. Sertoli Cells
  7. 7. Structure of the Testis2. Spermatogenic cells (schematic, schematic). As they develop, these cells move from the basal layer of the seminiferous tubule toward the lumen, thereby giving the epithelium its stratified appearance. You should identify the following cells/stages in spermatogenesis: 1. Spermatogonia (100X, 100X). These cells are primitive germ cells localized at the basement membrane of the epithelium. There are two basic types, but you do not need to distinguish between them. [Type A spermatogonia, which are the true germ cells, and Type B spermatogonia, which differ from the type A cells in that they represent the first step in spermatogenesis]. 2. Primary Spermatocytes (100X, 100X, 100X). The first stages of meiosis have begun. These cells are formed from the Type B cell. The nuclei of primary spermatocytes are large in size, and contain clumped checkerboard-like chromatin.
  8. 8. Structure of the TestisSpermatogenesis (cont): 3. Secondary Spermatocytes. These cells are formed when the primary spermatocytes complete the first meiotic division. These secondary spermatocytes complete the second meiotic division so quickly that few, if any, of these cells will be present on your slides. 4. Spermatids (100X, 100X). These haploid cells are formed from the secondary spermatocytes. These cells will undergo spermiogenesis (the formation of mature spermatozoa). These cells can be identified by their significantly smaller, dark nuclei and by their position closer to the lumen of the tubule. Note that late spermatids look very much like spermatozoa; they can be distinguished because late spermatids are still embedded within Sertoli cells. (schematic, 40X, 40X). 5. Spermatozoa (100X). These cells are closest to the lumen of the tubule. Their nuclei are very small, dark, and oblong. Look for their flagella (100X) protruding into the lumen of the tubule. Spermatozoa may also be free in the lumen of the seminiferous tubule.
  9. 9. Interstitium of Testis• Look in the spaces between the seminiferous tubules, and identify connective tissue elements, blood vessels, and nerves (50X).• Identify Interstitial Cells of Leydig (40X, 50X, 100X). These large endocrine cells synthesize and secrete testosterone.
  10. 10. Leydig Cells
  11. 11. Male Genital DuctsThe genital duct system is composed of seven histologically distinct zones: straight tubules, rete testis, ductuli efferentes, ductus epididymis, ductus deferens, ampulla of the ductus deferens, and ejaculatory duct. The first three are found within the testis.
  12. 12. Straight Tubules (Tubuli Recti)• At the apex of each testicular lobule, convoluted seminiferous tubules are replaced by short, straight seminiferous tubules (10X, 40X, 100X). Only Sertoli cells are present in the tubule epithelium, which is now simple columnar. The straight tubules are very short, and therefore difficult to find.
  13. 13. Rete Testis• Look in the testicular mediastinum, and identify the straight tubules opening into a network of interconnected ducts of variable caliber, the rete testis (2X, 10X, 40X). The irregularity of the rete testis lumen is an identifying characteristic.
  14. 14. Ductuli Efferentes (Efferent Ductules)• Arising from the rete testis and emerging from the mediastinum of the testis are 10-15 efferent ductules (2X, 20X). Note the alternating groups of tall and short columnar cells, which give the epithelium a very irregular, undulating or scalloped appearance (20X, 100X).• Note that many of the tall columnar cells are ciliated (100X); these cells transport spermatozoa along the duct. These are the only true motile cilia in the entire genital duct system.• Identify a thin layer of circularly arranged smooth muscle fibers (20X) just external to the basement membrane of the epithelium. What is the function of this smooth muscle?
  15. 15. Ductus Epididymis• Formed by several coalescing efferent ductules, the ductus epididymis (2X, a single duct) forms the body and tail to the epididymis. Note the characteristic, regular outline of the lumen (20X), and the even height of the epithelial cells that bear numerous stereocilia (extra-long non-motile microvilli). Compare this lumen to that of adjacent efferent ductules.• Note that this epithelium (10X, 50X) is pseudostratified columnar, with basal and tall columnar cells.• Identify the circularly-arranged smooth muscle layer (10X) external to the epithelium.
  16. 16. Ductus Epididymis stereocilia
  17. 17. Ductus Deferens (Vas Deferens)• This is a thick-walled, non-coiled, muscular tube that transports the spermatozoa from the epididymis to the urethra (2X, 4X).Mucosa• Identify pseudostratified epithelium (20X, 50X). Why is this type of epithelium called pseudo- stratified?• Identify apical stereocilia (50X) on the tall epithelial cells (except in the ampullar region).• Note that the entire mucosa is thrown into longitudinal folds (20X), giving the lumen a characteristic stellate (star-shaped) Note: 3 muscle layers appearance. Inner= longitudinal Middle= circular Outer= longitudinal
  18. 18. Ductus Deferens (Vas Deferens)Muscularis• Identify the three layers of smooth muscle (10X) that comprise the thick muscularis: inner longitudinal layer (40X), thick middle circular layer (40X, 40X), and thick outer longitudinal layer (40X).Adventitia. This region is located external to the muscularis, and within the spermatic cord.• Identify skeletal muscle (2X, 4X, cremasteric muscle), arteries (10X, 20X), nerves (10X, 40X), lymphatics, and pampiniform plexus (2X, 10X, anastomosing veins).• Note that the veins of the pampiniform plexus have unusually thick walls (20X), and, at first glance, look like arteries.
  19. 19. Ampulla of Ductus Deferens• This represents the enlargement of the terminal portion of the ductus deferens (schematic). The mucosa (10X) is extensively folded to form deep diverticula and pocket- like recesses. The muscularis is irregularly arranged, but a distinct outer longitudinal smooth muscle layer (10X, 40X) remains. A specific slide of this structure is not present in your slide collection.
  20. 20. Ejaculatory Ducts• Each ejaculatory duct (one on each side) is formed by the union of the ampulla of the ductus deferens with the excretory duct of the seminal vesicle (see below).• The ducts course through the prostate gland to enter the urethra (0.3X; 0.3X; 0.6X).• Note that the ejaculatory ducts have a simple columnar epithelial lining (5X; 40X).• Identify smooth muscle in the wall of the ejaculatory duct (5X; 20X). What is the function of this smooth muscle? Prostate gland
  21. 21. Male Urethra• The male urethra is part of the urinary system as well as the male reproductive system. There are three structural portions: the prostatic urethra, membranous urethra, and penile urethra. Anywhere along the urethral mucosa, small depressions or pits of mucosal acini can be found; these are known as glands of Littré.
  22. 22. Prostatic Urethra• So called because the prostate surrounds the urethra as it extends from the bladder. The epithelium is the transitional type, as in the bladder. The muscularis has an inner longitudinal and outer circular layer of smooth muscle arranged as scattered bundles.
  23. 23. Membranous Urethra• This segment of the urethra, about 1cm in length, exits the prostate and perforates the perineal membrane to enter the penis.• Note that the mucosal epithelium (40X) is pseudostratified or stratified columnar.• Identify smooth muscle fibers in the wall of this portion of the urethra (0.3X).• The membranous urethra is also encircled by a sphincter of skeletal muscle fibers (0.3X) from the deep transverse perineal muscle.
  24. 24. Penile Urethra• This portion of the urethra passes through the corpus spongiosum (see below) of the penis.• Note that the mucosal epithelium (40X) is psuedostratified or stratified columnar, with terminal portions becoming stratified squamous. It is surrounded by the spongiosum of the penis.• Identify glands of Littré (20X).
  25. 25. Auxillary Glands• Associated with the genital ducts are three auxiliary glands: seminal vesicles, prostate, and bulbourethral glands. These glands add secretions to the spermatozoa to form the semen.
  26. 26. The Seminal Vesicle• These paired glands are actually outpocketings of the ductus deferens and are located in the vicinity of the ampulla of the ductus deferens (2X), which is not present in this slide. The seminal vesicles secrete a yellowish, viscid fluid that is rich in fructose, and that comprises about 20% of semen volume.The Mucosa• Identify the large highly convoluted lumen (2X), which contains extensive mucosal foldings that give a honeycomb appearance.• Note that the epithelium consists of secretory cells (10X, 40X, 100X) in a pseudostratified columnar, or sometimes simple columnar, arrangement.Muscularis• Identify inner circular and outer longitudinal smooth muscle layers (4X, 40X) of the sheath.
  27. 27. The Prostate• A single gland that surrounds the ejaculatory ducts, the prostate is a composite of 30-50 tubulo-alveolo-saccular glands that secrete a thin, alkaline, milky fluid that is high in acid phosphatase, fibrinolysin, and citric acid. This secretion accounts for 75% of semen volume.Capsule• Under low magnification, identify the capsule (2X) of fibroelastic connective tissue (containing smooth muscle cells, 20X) that surrounds the entire gland, and is continous with the connective tissue septa and stroma (50X).Secretory Units• Identify secretory alveoli and tubules (4X, 20X). Note that these are quite irregular and have large lumens.• Identify prostatic concretions (4X, granules). These granules appear as multi-layered acidophilic material and they are a distinguishing feature of the prostate gland.• Note that the epithelium of the prostate gland (20X, 50X) is composed of simple columar to pseudostratified columnar epithelium.
  28. 28. Bulbourethral Glands (Cowper’s Glands)• These small, paired mucous-type glands (1X, 2X) are embedded in the connective tissue that surrounds the membranous urethra. They produce a specialized mucus that is secreted into the posterior portion of the cavernous segment of the urethra.• Identify skeletal muscle fibers (4X, 20X) outside the capsule.• Identify smooth muscle and skeletal muscle within the connective tissue septa of the gland. Smooth muscle and elastin fibers can be found in the intralobular connective tissue.• Examine the secretory units (4X, 40X); note that these tubulo- alveolar glands are lined with cuboidal or columnar epithelium.
  29. 29. Major Structural Components (Erectile Tissue)• The penis contains a core of erectile tissue within a fibrous tunica albuginea (1X). These structures are surrounded by a layer of loose connective tissue that contains blood vessels, nerves, and the occasional Pacinian corpuscle (1X; 10X). The looseness of this C.T. layer (1X) prevents damage to the overlying skin as it moves longitudinally during intercourse. What is the function of the mechanoreceptors in this location?Corpus Cavernosa Urethra (Corpus Spongiosum). The urethra passes through this structure (1X, 4X).• Identify large cavernous sinuses (4X, 20X), and fibroelastic connective tissue trabeculae with smooth muscle fibers (20X), throughout this erectile tissue.Corpus Cavernosum Penis. These paired erectile bodies (1X, 4X) are located dorsally.• Note that their structure (4X) is very similar to that of the corpus spongiosum.• Identify sinuses and smooth muscle (20X).
  30. 30. Blood Supply to Penile Erectile TissueDeep arteries (4X, 10X).• Note that only one is present in each erectile body.Helicine arteries.• Identify these spiralled arteries (1X, 2X) in the flaccid penis.Cavernous spaces (sinuses) located within the erectile tissues.• Identify these spaces (20X), and note that they are filled by blood from the helicine arteries, and lined with endothelial cells.
  31. 31. Female Reproductive System The female reproductive system has four maincomponents: ovaries, the genital tract (uterine tubes,uterus, and vagina), external genitalia and mammary glands. Throughout the reproductive period, these components undergo cyclic changes in structure and function, under the control of hormonal and nervousmechanisms. In addition to the studying the four main components, we will briefly discuss oogenesis and examine the stages of follicular development.
  32. 32. Ovaries: General Structure• Surface epithelium: Note that this is a simple cuboidal epithelium (40X), sometimes incorrectly called "germinal epithelium". Most of this epithelium is not present on your slides due to tissue processing, but some remnants should be present.• Tunica albuginea: Identify this thin, fibrous connective tissue layer (20X, 50X) directly underneath the surface epithelium. Ova must cross this layer to be released at ovulation.
  33. 33. Ovaries: General Structure• Cortex: The cortex (1X, 4X) comprises the major portion of the ovary. – Note the presence of many ovarian follicles (4X) of various sizes within the connective tissue stroma of the cortex. – Note that the connective tissue (50X) contains closely-packed, fine collagenous and reticular fibers.• Medulla: Identify the stroma (50X, 50X), a loose, highly-vascularized fibroelastic connective tissue with scattered smooth muscle cells. Note that the medulla is continuous with the hilum of the ovary (1X). The hilum of the ovary may not be apparent in some slides due to the plane of section.
  34. 34. Ovaries: Ovarian Follicles• There are 5 main types of follicles, classified according to their stage of development. The follicles present in the cortex represent ova and their associated follicular cells at various stages of development.
  35. 35. Ovaries: Primordial Follicles• These are the most primitive, and most abundant, type of follicle. Each follicle contains a primary oocyte (a female germ cell which has been sustained in the prophase stage of meiosis I since fetal life). Identify the single layer of squamous follicular cells (100X, 100X) surrounding the primary oocyte.• Study the oocyte (100X, 100X) at higher power. Note the relatively sparse cytoplasm (compared to the more mature oocytes), and a very prominent nucleolus (100X) within a large nucleus.
  36. 36. Ovaries: Primary Follicles• Upon appropriate hormonal stimulation, primordial follicles are induced to develop into primary follicles.Early primary follicle.• Note that the single layers of follicular cells (100X, 100X) become cuboidal to low columnar in shape.Late primary follicle.• Identify an extracellular, glycoprotein- containing layer, the zona pellucida (50X, 50X), between the oocyte and follicular cells.• Note that the follicular cells have proliferated to form a stratified layer of cells, the stratum granulosum; the cells are now called granulosa cells (50X, 50X).• Identify the connective tissue capsule, the theca folliculi (50X, 50X), that has formed external to the granulosa cells.
  37. 37. Primary Follicle
  38. 38. Ovaries: Secondary (Antral) Follicles• At this stage of development, fluid-filled spaces within the stratum granulosum have developed, forming the follicular antrum (50X). Note that the zona pellicuda (the basement membrane-like extracellular matrix between the oocyte and granulosa cells) has become prominent (20X, 50X).• Identify the prominent basement membrane (100X) now surrounding the follicle, known as the glassy membrane.
  39. 39. Secondary (Antral) Follicle Antrum Zona pellucida
  40. 40. Ovaries: Graafian Follicles• The Graafian follicle is the mature follicle, and is quite large. The increase in its size is primarily due to the increase in the size of the follicular antrum. Normally, in humans, only one of these follicles will actually be ovulated during each menstral cycle. Find a Graafian follicle (20X), and note that the stratum granulosum has thinned as the antrum has increased in size.• Identify the cumulus oophorus (40X). During formation of the antrum, the oocyte and a portion of the follicular cells become eccentrically located within the follicle; this eccentric mound of granulosa cells is the cumulus oophorus.• Identify the corona radiata (20X, 40X). This structure is formed from those granulosa cells that are directly associated with the oocyte. These cells will accompany the oocyte after ovulation.• Note that, at this stage, the theca folliculi has differentiated into two layers (100X), the theca interna and the theca externa.• Identify the theca interna, and note that it is the more vascularized of the two layers (100X). It is responsible for estrogen production.• Identify the theca externa (100X, 100X), and note that it is composed of a simple connective tissue layer.
  41. 41. Graafian Follicle at Ovulation• The oocyte and the corona radiata separate from the cumulus oophorus.• The primary oocyte completes meiosis I and becomes a secondary oocyte. It then undergoes its second maturation division, which will only proceed to metaphase II. It will only complete cell division if fertilization occurs.• The follicle ruptures by accumulation of fluid in the antrum. This is a rare occurrence; you will not see it in your slides!• The ovum, with the corona radiata, is released into the peritoneal cavity and taken up into the uterine tube.• The remaining portions of the follicle develop into a corpus luteum.
  42. 42. Corpus Luteum (Non-Pregnant)• This is the follicle remnant after ovulation; it will develop into a temporary endocrine structure. The corpus luteum forms by the proliferation of the granulosa cells, and the differentiation of those cells into progesterone-producing cells. Non-pregnant state. The corpus luteum contains the differentiated granulosa cells, now referred to as granulosa lutein cells (10X, 50X).• Try to find a yellowish pigment that can sometimes be observed in granulosa lutein cells.• Identify theca lutein (10X, 50X) or paralutein cells, which are cells of the theca interna that continue to produce estrogen during the post-ovulation period.• Look for a central blood clot or empty cavity (10X) that may be observed in the antrum of this newly formed corpus luteum (dependent on plane of section).• O-37 (Ovary, 7 months pregnancy; H&E) E-37 (Ovary, 7 months pregnancy; trichrome)• Corpus luteum of pregnancy (2X). Note the size of this structure relative to the entire ovary. It is very large and in many of the slides it appears to occupy most of the ovary.• E-56 (Ovary; PAS)• Corpus albicans. This is the involuted form of the corpus luteum, the remnant form of a corpus luteum that develops if pregnancy does not occur, or postpartum. Note that the corpus albicans (4X) is rather acellular and avascular, and resembles scar-like connective tissue.
  43. 43. Corpus Luteum Granulosa lutein Central blood clot or empty cavity
  44. 44. Corpus Luteum (Pregnant)• Note the size of this structure relative to the entire ovary. It is very large and in many of the slides it appears to occupy most of the ovary.
  45. 45. Corpus Albicans• This is the involuted form of the corpus luteum, the remnant form of a corpus luteum that develops if pregnancy does not occur, or postpartum.• Note that the corpus albicans (4X) is rather acellular and avascular, and resembles scar- like connective tissue.
  46. 46. Atretic Follicles• These are follicles that failed to reach maturity, and are now degenerating. This event can occur at any stage of development, and the resulting follicles vary greatly in appearance.• Try to find an atretic follicles (40X), which often contain remnants of the zona pellucida or the glassy membrane, and dead granulosa cells in the antrum.
  47. 47. Atretic Follicles
  48. 48. The Genital Tract• This portion of the female reproductive system consists of oviducts, uterus, and vagina. Each of these is a hollow structure with a wall of smooth muscle, a mucosal lining, and a covering of serosa or adventitia.
  49. 49. The Oviducts• After ovulation, the ovum is drawn into the infundibulum of the oviduct. Thereafter, it passes through the ampulla, isthmus, and intramural regions of the oviduct before entering the uterus.• 3 layers: – Mucosa: Note that the epithelium (100X) is simple columnar, and that some cells are ciliated. Non-ciliated cells are thought to secrete nutritive material for the ovum. – Muscularis: Identify an inner circular (40X) and an outer longitudinal (10X, 20X) smooth muscle layer. – Serosa: This is actually a reflected peritoneum. Identify the mesothelium (20X) on the outermost portion of these organs.
  50. 50. Portions of the Oviduct• Infundibulum (2X). This is a funnel-shaped portion of the oviduct that opens into the peritoneal cavity. Note that it has numerous fringed extensions of the epithelium, called fimbriae (10X), extending into the peritoneal cavity toward the ovary.• Ampulla (2X, 2X, 10X). This segment constitutes two thirds of the length of the oviduct. Note that this region is thin-walled, and has a large luminal area (10X) with a mucosa that is thrown into exaggerated, branching folds.• Isthmus (2X, 10X). Note that the lumen (10X) is much less folded here than in the ampulla, and it is more stellate (star-shaped).• Note that the outer muscular layers (40X) are thick and compact.• Intramural region (within the uterus) (2X). Note that folds of the mucosa (4X) are reduced to small bulges in this segment.• Note that the muscle layers blend into the myometrium (4X) of the uterus, while the mucosa blends into the uterine endometrium.
  51. 51. The Uterus• The uterine mucosa undergoes marked cyclic changes, and the muscularis is considerably more substantial than in the oviduct. The two major anatomical divisions of the uterus are the body and the cervix. The uterine wall has three layers: endometrium, myometrium, and perimetrium.• Perimetrium: Identify the simple squamous epithelium (mesothelium, 40X) of the serosal layer.• Myometrium: Identify three layers of smooth muscle: innermost longitudinal (4X, 20X), middle circular and oblique (4X, 20X), and outermost longitudinal (4X, 20X). These can be difficult to distinguish in some slides.
  52. 52. The Uterus• Endometrium: – Both the cervix and the body of the uterus are induced by ovarian activity to undergo cyclic changes, although those of the body of the uterus are considerably more pronounced and complex. – Epithelium • Simple columnar epithelium. Note that the epithelium invaginates into uterine (endometrial) glands (2X, 10X, 40X) that extend through the entire thickness of the endometrium. Uterine glands are simple, tubular glands with some basal branching. – Lamina propria (10X) • This is composed of irregular, stellate cells and reticular fibers and is unusually thick (2X). – Stratum basalis (basal layer) • Note deep straight arteries (4X, (10X) in the endometrial layer next to the myometrium. • Identify coiled arteries (4X, 20X) lying slightly more superficially.
  53. 53. The Uterus• Endometrium (cont.): – Stratum functionalis (functional layer). This layer is lost at menstruation. It is made up of two sublayers, the stratum spongiosum and stratum compactum. • Stratum spongiosum (spongy layer). This middle zone exhibits a spongy stroma due to edema. – Identify the characteristic corkscrew-shaped uterine glands (2X, 4X, 10X) in the progestational phase. – Identify the characteristic spiralled arteries (20X). • Stratum compactum (compact layer). This superficial layer has a relatively compact appearance. – Identify the straight neck portion of the uterine glands (20X) near the endometrial surface.
  54. 54. Corkscrew Uterine Glands of the Stratum Spongiosum Straight neck portion of glands in the stratum compactum
  55. 55. Endometrial Cyclic Changes• Cyclic changes occur in the endometrium, whereby the endometrium passes through four phases (i.e. proliferation, secretion, ischemic, and menstruation phases). You should note the histological characteristics of endometrium during each of these phases: – Proliferative (Follicular) Phase – Progestational (Secretory or Luteal) Phase – Ischemic (Premenstrual) Phase – Menstrual Phase
  56. 56. Proliferative (Follicular) Phase• During this phase, mitosis is occurring in both lamina propria stroma and epithelial glands.• Note that, early in this phase, the stratum functionalis is relatively thin, and that the epithelium is low columnar.• Note that, by the late proliferative phase (2X), the glands are considerably longer with larger lumens, and the functionalis becomes packed with glands.
  57. 57. Progestational (Secretory/Luteal) Phase• The three strata are most readily identified at this stage. Early in this phase, profuse glandular secretion begins.• Examine the epithelium (40X) on higher power, and note that cells are now tall columnar (why?).• Note that, by late secretory phase, glands take on a "saw- tooth" or "corkscrew" appearance (2X, 4X, 10X).• Identify spiral arteries (10X) extending nearly to the endometrial surface.• The stratum basalis remains firmly attached to the myometrium. Note that the ends of the tubular endometrial glands (10X) extend into this deepest layer.
  58. 58. Ischemic (Premenstrual) Phase• Coiled arteries constrict intermittently. They play a major role in the menstrual stage.
  59. 59. Menstrual Phase• At this time, the ischemia caused by the constriction of the spiral arteries results in necrosis of the stratum functionalis. This is followed by the shedding of this layer.• Identify ruptured blood vessels (20X) and torn glands (20X) in this stage.• Note that the basal layer (10X), with remnants of the endometrial glands, remains intact.
  60. 60. Endometrium of Cervix• Identify the mucus-secreting, simple columnar epithelium on the luminal surface. Note that this epithelium is continuous with the moist, stratified squamous epitelium that covers the external (vaginal) surface of the cervix (20X).• Identify the mucosa and the underlying myometrium (10X).
  61. 61. Placenta• Identify the fetal surface (4X), which is covered by the simple cuboidal or squamous epithelium of the amnion (100X).• Identify the chorionic plate (1X ,4X), which is made up of dense connective tissue and which lies immediately under the amnion. The umbilical vessels of the fetal circulation branch through this plate.• Identify large chorionic stem (anchoring) villi (2X), which form connective tissue columns that span the width of the placenta from the fetal to the maternal side.• Identify small chorionic villi (4X), which branch from these stem villi; the small villi lie in the maternal blood that fills the intervillous spaces (10X). The villi (40X, 40X) themselves also contain blood vessels, which are branches of the fetal umbilical vessels. These vessels are surrounded by connective tissue (mesenchyme), and each villus is covered by trophoblastic cells.
  62. 62. Placenta• Examine the trophoblastic cells, and note that the innermost layer of cells, the cytotrophoblast (100X), forms a cubodial epithelium. The outer layer, which is more irregular and amorphous, is the syncytiotrophoblast (100X).• Identify the maternal side of the placenta, the decidua basalis (4X), to which the stem villi attach. This is modified endometrial tissue and can be identified by the presence of large decidua cells (10X, 40X).• Note that the endometrium merges with the myometrium of the uterus.
  63. 63. Umbilical Cord• Identify the two umbilical arteries (4X, 40X); these are unusual because the tunica media contains both an inner longitudinal and outer circular smooth muscle.• Identify the single umbilical vein (4X, 40X). The vein is unusual because its wall consists primarily of tunica media, rather than tunica adventitia as in other veins. This vein carries oxygenated blood from the placenta to the fetus.
  64. 64. The Vagina• The fibromuscular vaginal wall consists of mucosa, muscularis, and adventitia.Mucosa• Note that the vaginal mucosal epithelium (1X, 4X, 20X) is thick, non- keratinized stratified squamous.• Note that the portion of cervix protruding into the vagina is covered by the same type of epithelium (20X).• Identify mucosal rugae (mucosal foldings, 4X).• Note that the (10X, 20X). lamina propria contains abundant leukocytes (20X) and an extensive vascular plexusMuscularis• Identify two layers of smooth muscle (4X), an inner circular and an outer longitudinal layer (they may be somewhat indistinct).Adventitia
  65. 65. Female External Genitalia• In the female, the clitoris, labia minora, labia majora, and vestibular glands comprise the external genitalia, or vulva.
  66. 66. Mammary Glands• These are actually specialized cutaneous sweat glands located in the subcutaneous region. Merocrine and apocrine secretion both occur during lactation; lipid globules are released by an apocrine process, while milk protein is secreted by a merocrine process (schematic).• Examine both active (4X) and inactive (4X) mammary gland sections, and compare secretory lobules in these two conditions (schematic). Note the abundant C.T. (connective tissue) in resting mammary gland.• Identify myoepithelial cells (50X). What do they do here?• Identify mammary gland ducts (4X, 40X).