The Male Reproductive System Makes maintains and deposits

The Male Reproductive System Makes, maintains and deposits sperm, secretes sex hormones.

Organs Primary sex organs: Testes (gonads) l Accessory Sex Organs: l l l l l Vas Deferens Urethra Penis Ejaculatory duct Seminal Vesicles Prostate Bulbourethral gland Epididymis Scrotum

Male Repro Overview

Testes Ovoid, 5 cm long, 3 cm. in diameter l Inside the scrotum l Tough, white fibrous capsule on the outside l Divided into 250 lobules l l Each lobule contains 1 -4 seminiferous tubules, each 70 cm long uncoiled. Lined with spermatogenic cells. Interstitial cells lie between Sem. Tubules and secrete male sex hormones. Collect into the epididymis Epididymis becomes the vas deferens as it rises from the testes

The Testes

Sperm Cell Formation l Seminiferous Tubule epithelium has: supporting cells: support, nourish, regulate spermatogenic cells l Spermatogenic cells: give rise to sperm cells l l Sperm collect in the seminiferous tubule, then move to the epididymis to accumulate and mature

Sperm l Tiny cells: . 06 mm long l Has: Head: acrosome, chromatin in a nucleus l Midpiece: many mitochondria l Tail: several microtubules (flagellum) l

Spermatogenesis l Spermatogonia: undifferentiated, 46 chromosomes, in early adolescence, mitosis takes place l Some become primary spermatocytes, still 2 n l Meiosis takes place, secondary spermatocytes after first division, spermatids (4) after the second division l Spermatids mature into sperm cells

Male Accessory Organs: Epididymis l Tightly coiled, thin tube 6 meters long l Connects to ducts in testes l Immature, nonmotile sperm move in by peristalsis in epididymis, and then mature l Now sperm can swim

Male Accessory Organs: Vas Deferens l A. k. a. Ductus Deferens l Muscular tube, 45 cm. long l Ends behind bladder, joins with duct from seminal vesicle to form the ejaculatory duct, which passes through the prostate and empties into the urethra

Male Accessory Organs: Seminal Vesicle l Twisty, saclike structure 5 cm. long l Lining secretes a slightly alkaline fluid, counters acidity in urethra (and eventually the vagina) l Secretions also contain fructose and prostaglandins. Fructose nourishes sperm, prostaglandins stimulate uterine contractions in the female, helping to pull sperm up.

Male Accessory Organs: Prostate l Chestnut shaped, 4 cm. Long by 3 cm thick l Around urethra near base of bladder l Made of connective tissue with many glands which empty into the urethra l Secretions are thin, milky, alkaline, helps motility of sperm

Male Accessory Organs: Bulbourethral Glands l A. k. a. Cowper’s glands l 1 cm. in diameter l Behind prostate l Many tubes for secreting a mucuslike fluid which lubricates the end of the penis

Semen l l l Sperm and secretions from the accessory organs. p. H about 7. 5 Contains nutrients, mucus, and prostaglandins 2 -6 ml containing 120 million sperm per ml. Sperm undergo Capacitation: the ability to fertilize an egg involving the weakening of the acrosomal membranes