Male reproductive system

1. Male reproductive system

2. Physiological anatomy • Main structure are • Testes • Epididymis • Vas deferens • Seminal vesicles • Prostate gland • Urethra • Bulbourethral glands

3. Testes is composed of 900 coiled seminiferous tubules each more than half m long in which sperms are formed. Sperms empty into epididymis (coiled tube 6 m) leading to vas deferns which enlarges into ampulla of the vas deferns.Vas enters the body of the prostate .Two seminal vesicles on each side of prostate empty into the prostatic end of ampulla. Contents from ampulla and seminal vesicles enter ejaculatory

4. duct and then into prostatic urethra. Urethra is supplied with mucous derived from bulbourethral glands.

5. Male reproductive tract • Testes produce mature spermatozoa • Sperm enter epididymis • Elongated tubule with head, body and tail regions • Monitors and adjusts fluid in seminiferous tubules • Stores and protects spermatozoa • Facilitates functional maturation of spermatozoa

6. Male reproductive system

7. Spermatogenesis • Seminiferous tubules • Lined by germinal epithelium, containing • Spermatogonia • Stem cells involved in spermatogenesis • Different developmental stages of sperm • Sustentacular cells • Promote development of sperm • Spermeogenesis

8. Cross section of Seminiferous tubule

9. The Ductus Deferens and Accessory Glands

10. Spermatogenesis • Formation of sperm from spermatogonia • Primordial germ cells migrate into seminiferous tubule to line the tubule as spermatogonia • Mitosis of spermatogonia form more spermatogonia throughout the life after puberty • In female the primordial germ cells do not proliferate after formation in intrauterine life

11. Spermatogenesis

12. Spermatogenesis • Begins near the age of puberty – 13 years • Mitosis continues for formation of new spermatogonia • Spermatogonia migrate towards the central lumen • Covered by surrounding Sertoli Cells • Enlarge to form Primary spermatocyte • 2 stage meiosis (reduction division)

13. Spermatogenesis • 1st division • Primary spermatocyte (46 chromosomes-diploid number) →2 secondary spermatocytes (23 chromosomes- haploid number) • 2nd division • Each secondary spermatocyte (haploid) → 2 spermatids • So each primary spermatocyte → 4 spermatids • Each spermatid is converted into sperm • ½ of the sperm contain X chromosome • ½ of the sperm contain Y chromosome

14. Spermatogenesis

15. Formation of sperm • Spermatids are epithelioid cells • Modified/differentiated to form sperms • Head --- Condensed nucleus,thin cytoplasm. • Acrosome --- Golgi complex • Contains Hyaluronidase and proteolytic enzymes • These enzymes allow sperm to enter the ovum and fertilize it. • Tail or Flagellum --- • Central axoneme- 11 microtubule • Cell membrane covers the axoneme • Mitochondria collected in proximal thick portion- the body of the tail

16. Spermiogenesis

17. The sperm

18. HORMONAL FACTORS THAT STIMULATE SPERMATOGENESIS • Testosterone –interstitial cells of leydig-essential for growth and division of the testicular germinal cells. • LH –ant pit –stimulates leydig cells. • FSH-ant pit-stimulates sertoli cells-converts spermatids to sperm.

19. Growth hormone –promotes early division of spermatogonia themselves– control background metabolic function of testes.

20. Maturation of sperm • Freshly formed sperms in seminiferous tubules are nonmotile and hence non fertile • Develop motility while in epididymis for 18-24 hours • Don’t exhibit motility before ejaculation • Storage of sperms in epididymis. Vas deferens. Specially ampulla of VD • Fertile even after one month • Kept inactive during storage • Become motile after ejaculation

21. Physiology of mature sperm • Capable of flagellated movement • Velocity = 1-4 mm/min • ↑ activity in neutral or slightly alkaline medium • ↓activity in acidic medium • ↑temperature→ ↑activity but ↓ life span • Life span after ejaculation = 24 – 48 hours

22. Accessory glands • Seminal vesicles • Prostate gland • Bulbourethral glands • Secrete alkaline mucus with lubricating properties

23. Seminal vesicles • Secrete mucoid secretion containing • Fructose – nutrition • Citric acid- nutrition • Prostaglandins – help fertilization • Make cervical mucus more receptive to sperm • Reverse peristalsis in uterus & FT to move the ejaculated sperm toward the ovaries. • Fibrinogen- clots semen • Empties into ejaculatory duct after VD • Adds to the bulk of semen • Contributes ~60% total volume of semen

24. Prostate Gland • Secret thin milky alkaline fluid containing • Calcium ions • Citrate ions • Phosphate ions • Clotting enzyme • Profibrinolysin • Capsule contracts along with VD • Adds to the bulk of semen • Alkalinity neutralizes the acid contents of semen and vaginal secretions (pH 3.5 – 4 )

25. Sperms become motile at 6—6.5

26. Semen • Contents of VD =10 % • Secretion of seminal vesicles =60 % • Prostatic secretion and others glands = 30 % • pH 7.5 • Enzyme in prostatic fluid clots the fibrinogen of seminal vesicles that holds semen in female genital tract. • Profibrinolysin of prostatic secretion →fibrinolysin → dissolution the clot after about 15 minutes • Sperms are fertile for 24 – 48 hours after ejaculation • Can be stored for long duration at very low temperature ( – 100 ºC)

27. Capacitation • After ejaculation multiple changes causing the sperm to become motile and fertile • Uterine and FT secretion wash away the inhibitors that supress sperm activity. • In male genital tract constant flow and supply of floating vesicles from Seminiferous tubules containing cholesterol keep the acrosome tough – no such supply after ejaculation • Membrane of sperm becomes thin-- Calcium in the semen helps the flagellated movement. • Release of acrosomal enzymes help digging their pathway

28. Acrosomal reaction • For dispersal of granulosa cells • Penetration of ovum by the sperm . • Hyaluronidase depolymerizes the hyaluronic acid polymers that hold the granulosa cells together • Proteolytic enzyme digest the structural elements

29. Acrosomal reaction • Ant memb of the sperm binds with receptor proteins of the zona pellucida. Acrosomal membrane dissolves and all the enzymes released. • make an opening in Z. Pellucida for entry of the head of the sperm • Membrane covering the head fuses with the sperm cell membrane to complete number of 23 paired chromosomes (fertilization)

30. Entry of one sperm only • Penetration of 1st sperm→ diffusion of Large No of Ca++ through the oocyte → exocytosis of cortical granules into perivitelline space • These granules contain substances to diffuse into meshwork of Z pellucida and make it repulsive to entry of more sperms.

31. Abnormal spermatogenesis • Post mumps orchitis • Stricture and degeneration of germinal epithelium • Excessive temperature of the testes • Cryptorchidism (undescended testes)

32. Effect of temperature • ↑temperature in the testes →degeneration of the germinal epithelium→ infertility • Temperature in the scrotum is 2 ºC lower • Cryptorchidism → ↑temperature in the testes→ degeneration of germinal epithelium→ infertility • Cryptorchidism may be due to • Some obstruction along the path of the descent • Deficiency of testosterone in intrauterine life

33. Sperm count • Volume of semen per ejaculate = 3.5 ml • Average sperm count = 120 million/ml • Normal range = 35-200 million/ml • Count < 20million/ml→ infertility Abnormal morphology and motility of sperms also cause reduced fertility

34. Abnormal morphology of sperms

35. Thank-you Questions ??