Male Reproductive System.

1. Male Reproductive System. Prof. K. Sivapalan.

2. Structure • Ureter • Vase Difference • Ampula • Seminal Vesicle • Prostrate • Urethra • Epididimis • Testes • Prepuce Male Reproductive system

3. Blood Testis Barrior- • Tight junctions between adjacent Sertoli Cells. • This prevents large molecules penetrating. • Steroids can diffusebecause of fat solubility. • Fluid in seminiferous tubules is different from plasma- low glucose and protein. Rich in androgens, estrogens, K+, inositol, glutamic acid and aspartic acid. Male Reproductive system

4. Spermatogenesis • Spermatogonia [Primitive germ dells] begin mitotic division. • Primary spermatocytes undergo meiotic [reduction] division. • Secondary spermatocytes • Early Spermatids • Late Spermatids- develop tail. • Spermatozoa. • The descendants remain tied to Sertoli cell until the late spermatid state. • One spermatogonium – 512 spermatozoa [74 days]. Male Reproductive system

5. Sperm. • Head- chromosomal material. • Acrosome- cap on head, rich in enzymes for penetration corona radiata and ovum. • Proximal portion of the tail is wrapped in a membrane packed with mitochondria. • Capability of motility develops as it moves through epididimis. • Several inhibitory proteins in the fluid inhibit motility until ejaculation. Male Reproductive system

6. Effects of Temperature- 32°C • Air circulating around the scrotum. • Counter current exchange between spermatic arteries and veins. • Un-descended testes, testes wrapped closely with body by tight binders- degeneration and sterility. • Hot baths- 43 – 45° for 30 minutes and insulated supporters reduce sperm count by 90 %. Male Reproductive system

7. Effect of Hormones. • Leutinizing Hormone- stimulate Testosterone secretion. • Testosterone is essential for growth and division of germinal cells. • Follicular Stimulating Hormone- stimulates Sertoli cells. Absence- no maturation of sperms. • Estrogens produced by testis is also essential. • Growth hormone and other hormones also necessary. Male Reproductive system

8. Function of Seminal Vesicles. • Secrets mucoid material with fructose, citric acid, other nutrients, prostaglandins and Fibrinogen. • Seminal vesicles empty their contents during emission into ejaculatory duct. • Prostaglandins may- • modify cervical mucus for sperm motility and • reverse peristalsis in uterus and fallopian tubes to facilitate sperm motility. • Largest volume contribution to the semen. Male Reproductive system

9. Function of the Prostate. • Secrets thin milky fluid with calcium, citrate, phosphate, a clotting enzyme and profibrinolysin. • Empties during emission by contraction of the capsule and ads to bulk of the semen. • Alkalinity essential to neutralize the acidity of the seminal vesicular fluid and vaginal secretions. Male Reproductive system

10. Semen. • Sperm and vas deferens fluid- 10 % • Fluid from seminal vesicle- 60 % • Fluid from prostate- 30 %. • The pH is 7.5, 2.5 to 3.5 ml. • Sperm count- 100,000,000 per ml. • Clotted on ejaculation [fibrinogen from seminal vesicle and clotting enzyme from prostate] • The coagulum dissolves in 15 to 30 minutes [prostatic profibrinolysin activated] • Life of ejaculated sperm is about 48 hours. [storage in Vas deference 42 days] Male Reproductive system

11. Abnormalities of Spermatogenesis. • Infections- bilateral orchitis due to mumps. • Inborn degenerate tubular epithelia due to strictures in genital ducts. • Excessive temperature of the testes due to failure to descend [cryptorchidism] and hot environment. Male Reproductive system

12. Endocrine Function of Testes. • Secretion of Testosterone-4-9 mg/day • Transport- 98% in plasma is bound to protein. • 65% bound β globulin- gonadal steroid binding globulin. • 33% bound to albumin. • Plasma level- 300-1000 ng/dl [10.4-34.7 nmol/L] in males, 30-70 ng/dl in females. • Converted to 17-ketosteroiod and excreted in urine. Male Reproductive system

13. Secretion of Testosterone and Spermatogenesis. Male Reproductive system

14. Actions of Testosterone. • Feed back control of LH secretion. • Maintain spermatogenesis along with FSH. • Develop and maintain male secondary sexual characteristics. • Protein anabolic and growth promoting effect. Male Reproductive system

15. Secondary Sexual Characteristics. • External Genitalia • Penis increases in length and width. • Scrotum becomes pigmented and rugose with testicular enlargement. • Internal Genitalia. • Seminal vesicles enlarge and secrete. • Prostrate and bulbourethral glands enlarge and secrete. • Voice becomes deeper- • Larynx enlarges. • Vocal cords increase in length and thickness. • Body conformation- • Shoulders broaden, all bones matrix increased. • Narrow pelvic outlet, [male pelvis] • Muscles enlarge [50% more than female]. Male Reproductive system

16. Secondary Sexual Characteristics-2. • Hair growth- • Beard appears. • Anterior hair line recedes. • Pubic hair with male pattern [triangle with apex up] • Hair appears in axilla, chest, around anus and increase in body hair. • Scalp hair decreases. • Skin- • Sebaceous gland secretion thickens and increases. • Increased melanin. • Mental- • More aggressive, active attitude. • Interest in opposite sex. Male Reproductive system

17. Other Effects. • Anabolic Effects. • Growth rate increased by increased synthesis and reduced breakdown of protein. • Fusion of epiphysis- ? Estrogen [in males, conversion of testosterone.] • Moderate retention of sodium, potassium, calcium, sulfate, and phosphate. • Metabolic rate increased. • Red cell count increased. • Libido- • Increased. Male Reproductive system

18. Production of Estrogens in Males • 80 % of estradiol and 95 % of estrone in plasma is formed by extragonadal aromatization of circulating testosterone. • The remainder comes from testes. • Plasma estradiol- 20-50 pg/dl. • Production increases with advancing age. Male Reproductive system

19. Functions of Testosterone During Fetal Development. • Testosterone is responsible for the development of the male sex organs. • Descent of testes. Male Reproductive system

20. Regulation of Gonadotropin and Testosterone Secretion. • Chorionic gonadotropin stimulates secretion in fetus. • GNRH from hypothalamus stimulates LH and FSH from pituitary. • Testosterone inhibits LH and Inhibin inhibits FSH at both levels. • Psychic factors through limbic system influence GNRH secretion and sexual functions- stress can inhibit. Male Reproductive system