The Male Reproductive System

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The Male Reproductive System

  1. 1. Ch 27: Reproductive System <ul><li>Goals: </li></ul><ul><li>Identify the structures of the male and female reproductive systems, including the gross and microscopic anatomy of the organs, structures and accessory glands and their basic functions. </li></ul><ul><li>Explain meiosis, spermatogenesis and oogenesis. </li></ul><ul><li>Discuss the changes that occur in the female reproductive system during pregnancy. </li></ul>
  2. 2. General Organization <ul><li>Gonads  gametes & hormones </li></ul><ul><li>Ducts  transport of . . . ? </li></ul><ul><li>Glands  secrete fluid </li></ul><ul><li>Perineal structures = external genitalia </li></ul>
  3. 3. Male Reproductive Anatomy <ul><li>Primary reproductive organs produce gametes </li></ul><ul><li>Secondary reproductive organs . . . </li></ul><ul><li>Male reproductive and urinary tracts are partially shared </li></ul>Fig 27-1
  4. 4. Testes (paired glands) <ul><li>Develop adjacent to kidneys </li></ul><ul><li>Descend into scrotum through inguinal canal (function of gubernaculum testis) </li></ul><ul><li>Peritoneal lining is carried along  lining of scrotum </li></ul><ul><li>Spermatic cord: bundle containing all the “duct work” </li></ul><ul><li>Cryptorchidism </li></ul>Figs 27-2/3 4 month
  5. 5. Cryptorchidism <ul><li>In 3% of full-term and 30% of premature deliveries </li></ul><ul><li>Significance? - Treatment? </li></ul>
  6. 6. Spermatic Cord Can be palpated as it passes over the pubic brim. Constituents : 1. Pampiniform plexus of spermatic vein 2. Spermatic artery 3. Ductus (vas) deferens 4. Lymphatics 5. Nerves-ilioinguinal and genitofemoral Fig 27.3
  7. 7. Scrotum <ul><li>Function: supports and protects testes </li></ul><ul><li>Structure: Skin & underlying superficial fascia </li></ul><ul><ul><li>Dartos muscle in dermis </li></ul></ul><ul><ul><li>Cremaster muscle - continuous with abdominal wall muscles (?) </li></ul></ul><ul><li>Involuntary contraction (cremasteric reflex) in response to ________ </li></ul><ul><li>Scrotal sac forms 2 separate chambers </li></ul>Cremaster muscle
  8. 8. Structure of Testes <ul><li>Fibrous capsule – tunica albuginea – surrounds testes </li></ul><ul><li>Scrotal cavity – lined by tunica vaginalis – parietal and visceral layers </li></ul><ul><li>200-300 lobules </li></ul><ul><li>3 seminiferous tubules </li></ul>Figs 27-4/5
  9. 9. From Spermatocyte to Spermatozoon <ul><li>Spermatogenesis : Meiosis of primary spermatocytes  spermatids </li></ul><ul><li>Spermiogenesis : Spermatid maturation into spermatozoa within Sertoli cells </li></ul><ul><li>Spermiation: Spermatozoon released into lumen </li></ul>
  10. 10. Sustentacular (Sertoli) Cells <ul><li>Maintenance of blood testis barrier </li></ul><ul><ul><li>special lumen fluid high in sex hormones, K + and aa </li></ul></ul><ul><ul><li>protection from immune attack ( due to sperm specific ag) </li></ul></ul><ul><li>Suspend spermatids and support spermatogenesis and spermiogenesis </li></ul><ul><ul><li> FSH and Testosterone work via Sertoli cells </li></ul></ul><ul><li>Secretion of inhibin to slow sperm production </li></ul><ul><li>Secretion of androgen-binding protein (ABP) </li></ul>
  11. 11. Anatomy of a Spermatozoon <ul><li>Mature sperm has 3 portions: </li></ul><ul><li>Head with acrosome (containing _______ ) </li></ul><ul><li>Middle piece with nucleus and lots of ? </li></ul><ul><li>Tail - flagellum - (rotating in corkscrew fashion) </li></ul>See fig 27-6
  12. 12. Epididymis <ul><li>~ 7 m long </li></ul><ul><li>Head - superior, receives spermatozoa </li></ul><ul><li>Body - distal and inferior </li></ul><ul><li>Tail - leads to ductus deferens </li></ul><ul><li>Functions: </li></ul><ul><li>1) Monitors and adjusts tubular fluid (stereocilia!) </li></ul><ul><li>2) Recycles damaged spermatozoa </li></ul><ul><li>3) Stores sperm and facilitates maturation </li></ul>Rete testis and Efferent ductules
  13. 13. Pathway of Sperm <ul><li>Seminiferous tubules </li></ul><ul><li>Rete testis </li></ul><ul><li>Epididymis </li></ul><ul><li>Vas (ductus) deferens </li></ul><ul><li>Ampulla of vas deferens </li></ul><ul><li>Ejaculatory duct </li></ul><ul><li>Prostatic urethra </li></ul><ul><li>Membranous urethra </li></ul><ul><li>Penile (spongy) urethra </li></ul>Fig 27.8
  14. 14. Accessory Glands <ul><li>Provide for 95% of the seminal fluid </li></ul><ul><li>1) Seminal Vesicles </li></ul><ul><li>Paired, on back wall of urinary bladder </li></ul><ul><li>Tubular (~ 15 cm) </li></ul><ul><li>Produce 60% of semen, hormones, fructose, etc. </li></ul><ul><li>Activate sperm (leading to motility) </li></ul>Fig. 27.8
  15. 15. Prostate Gland <ul><li>20 - 30% of seminal fluid </li></ul><ul><li>Single, doughnut-shaped </li></ul><ul><li>Secretion contains: </li></ul><ul><ul><li>Citrate </li></ul></ul><ul><ul><li>Seminal plasmin (mild antibiotic) </li></ul></ul><ul><ul><li>Prostate specific antigen (PSA) – blood test for ? </li></ul></ul>
  16. 16. Bulbourethral glands (Cowper’s glands) <ul><li>Pea size, paired, at base of penis </li></ul><ul><li>Produce about 10% of semen </li></ul><ul><li>Alkaline mucus - function?? </li></ul>
  17. 17. Semen <ul><li>2-5 ml ejaculate </li></ul><ul><li>Ejaculation of semen by pelvic floor and penile muscles (Sympathetic division induces peristalsis in tract) </li></ul><ul><li>Constituents: </li></ul><ul><li>1. sperm - 20 - 100 million sperm/ ml </li></ul><ul><li>2. seminal fluid - see above glands </li></ul><ul><li>3. enzymes - proteases and seminalplasmin </li></ul>
  18. 18. Penis <ul><li>Root - fixed to ischial ramus </li></ul><ul><li>Body with erectile tissues </li></ul><ul><li>Glans – enlargement of corpus spongiosum </li></ul><ul><ul><li>Prepuce - foreskin – partially covers glans and surrounds external urethral meatus (may be removed in circumcision ) </li></ul></ul><ul><ul><li>Preputial glands - produce smegma (supports bacterial growth, such as E. coli ) </li></ul></ul>Fig 27.9 The End

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