Male Reproductive System

1. Male Reproductive System • The male gonads (testes) produce sperm and lie within the scrotum • Sperm are delivered to the exterior through a system of ducts: epididymis, ductus deferens, ejaculatory duct, and the urethra • Accessory sex glands: • Empty their secretions into the ducts during ejaculation • Include the seminal vesicles, prostate gland, and bulbourethral glands

2. Male Reproductive System

3. The Scrotum • Sac of skin that hangs outside the abdominopelviccavity, at the root of the penis • Contains paired testicles separated by a midline septum • Its external positioning keeps the testes 3C lower than core body temperature (needed for sperm production) • temperature is kept constant by two sets of muscles: • Dartos – smooth muscle that wrinkles scrotal skin • Cremaster – bands of skeletal muscle that elevate the testes

4. The Scrotum

5. The Testes • Seminiferous tubules: • Produce the sperm • Converge to form the tubulusrectus • Sperm travel from the tubulusrectus  rete testis • From the rete testis, the sperm: • Leave the testis via efferent ductules enter the epididymis

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7. Epididymis • Efferent ductules release sperm into the Epididymis (which caps the superior aspect of the testis) • Passes nutrients to the sperm • Non-motile sperm enter, pass through its tubes and become motile • Upon ejaculation the epididymis contracts, expelling sperm into the ductus deferens

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9. The Penis External Penis Internal Penis • An organ that delivers sperm into the female reproductive tract • Attached root & free shaft • End of penis consists of foreskin • Circumcision – surgical removal of the foreskin after birth • Urethra and erectile tissue • Erectile tissue – spongy connective tissue and smooth muscle • Corpus spongiosum – surrounds the urethra • Corpora cavernosa –erectile tissue

11. Vas Deferens and Ejaculatory Duct Vas Deferens runs from the epididymis and joins the seminal vesicle to form the ejaculatory duct Propels sperm from the epididymis to the urethra

12. Urethra Conveys both urine and semen (at different times) Spongy, or penile – runs through the penis and opens to the outside at the external urethral orifice

13. Accessory Glands: • Seminal Vesicles- posterior wall of the bladder; makes up 60% of semen (alkaline fluid) volume; expels contents into the ejaculatory duct • Prostate Gland- doughnut shaped & encircles part of the urethra; milky acidic fluid is 1/3 volume of semen; activates sperm • Cowper’s Gland- pea sized gland; produces mucous to neutralize acidic urine in the urethra

14. Semen • Milky white, sticky mixture of sperm and accessory gland secretions • Provides a transport medium and nutrients (fructose), protects and activates sperm, and facilitates their movement • Facilitate the movement of sperm through the female reproductive tract • Only 2-5 ml of semen are ejaculated, but it contains 50-130 million sperm/ml

15. Ejaculation • The propulsion of semen from the male duct system • At ejaculation: • Reproductive ducts and accessory organs contract and empty their contents • The bladder sphincter muscle constricts, preventing the expulsion of urine • Bulbospongiosus muscles to undergo a rapid series of contractions • Propulsion of semen from the urethra

16. Spermatogenesis • Spermatogenesis: the sequence of meiotic events that produces haploid sperm (gametes) in the seminiferous tubules of the testes

17. Spermatogenesis • Cells making up the walls of seminiferous tubules are in various stages of cell division • These spermatogenic cells give rise to sperm in a series of events • Mitosis of spermatogonia, forming spermatocytes • Meiosis forms spermatids from spermatocytes • Spermiogenesis – spermatidsform mature sperm