Male Reproductive System. Prof. K. Sivapalan.

Male Reproductive system Structure Ureter Vase Difference Ampula Seminal Vesicle Prostrate Urethra Epididimis Testes Prepuce 2014 Male Reproductive system

Male Reproductive system 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. 2014 Male Reproductive system

Male Reproductive system 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]. 2014 Male Reproductive system

Male Reproductive system 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. 2014 Male Reproductive system

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 %. 2014 Male Reproductive system

Male Reproductive system 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. 2014 Male Reproductive system

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. 2014 Male Reproductive system

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. 2014 Male Reproductive system

Male Reproductive system 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] 2014 Male Reproductive system

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. 2014 Male Reproductive system

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. 2014 Male Reproductive system

Secretion of Testosterone and Spermatogenesis. 2014 Male Reproductive system

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. 2014 Male Reproductive system

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]. 2014 Male Reproductive system

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. 2014 Male Reproductive system

Male Reproductive system 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. 2014 Male Reproductive system

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. 2014 Male Reproductive system

Functions of Testosterone During Fetal Development. Testosterone is responsible for the development of the male sex organs. Descent of testes. 2014 Male Reproductive system

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. 2014 Male Reproductive system