Biology 322 Human Anatomy I Male Reproductive System
Human Reproductive System: - Begins developing in 4th week of embryonic development. - Remains “sexually indifferent” until 7th week in male 8th week in female
Male Female 7th & 8th Testes, penis, Clitoris, labia begin weeks scrotum begin development development Both sexes: Gonads (ovaries & testes) remain inactive until puberty, when anterior pituitary stimulates maturation
Reproductive System of Adult Male - Midsagittal
Reproductive System of Adult Male – Coronal from back
Spermatic Cord Vas Deferens Testicular Nerve, Artery & Vein Plexus containing Vas Deferens Testicular Nerve, Artery & Vein Plexus Cremaster Muscle (part of external oblique muscle) Epididymis Scrotum Testis
Testis or Testicle ~ 4 cm x 2 cm x 2 cm Surrounded by dense irregular connective tissue: Tunica Albuginea outside of which is pouch of peritoneum “dragged” into scrotum: Tunica Vaginalis
Testis or Testicle Each testis divided into approximately 250 Lobules separated by connective tissue septa Each lobule contains one to four coiled Seminiferous Tubules where Sperm are produced
Testis or Testicle One Seminiferous Tubule
Seminiferous Tubule
Testis or Testicle Sustentacular Cells Spermatogonia Primary Spermatocytes Secondary Spermatocytes Spermatids Sperm
Testis or Testicle Cells between seminiferous = tubules groups of Interstitial cells which secrete testosterone
Testis or Testicle Sperm pass from seminiferous tubule into tubulus rectus
Testis or Testicle Sperm pass from seminiferous tubule into tubulus rectus then into rete testis
Sperm pass from seminiferous tubule into tubulus rectus then into rete testis through efferent ductules
Sperm pass from seminiferous tubule into tubulus rectus then into rete testis through efferent ductules to epididymis
Epididymis Long, coiled tube In scrotum Posterior to testis Sperm take weeks to pass through epididymis where they mature: become fertile become motile Debris also removed in epididymis
Sperm from epididymis pass into vas deferens or ductus deferens which enters spermatic cord
Spermatic cord: Passes through inguinal canal into abdomen
Within abdomen, vas deferens passes to posterolateral side of bladder View
Within abdomen, vas deferens passes to posterolateral side of bladder where it ends as an enlarged ampulla Posterior View
Within abdomen are two accessory glands: the seminal vesicles and the prostate Posterior View
Seminal Vesicles Paired, posterior to bladder
Seminal Vesicles Paired, posterior to bladder Join with ampulla of vas deferens to form ejaculatory duct
Seminal Vesicles Paired, posterior to bladder Join with ampulla of vas deferens to form ejaculatory duct Produces ~60% of fluid in semen Contains nutrients for sperm chemicals to decrease viscosity of cervical mucous & stimulate peristalsis of uterus
Prostate Inferior to bladder Surrounds ejaculatory ducts and proximal part of urethra
Prostate Inferior to bladder Surrounds ejaculatory ducts and proximal part of urethra Produces ~30% of fluid in semen Contains chemicals to enhance sperm motility & clot & then liquify semen & neutralize acidity of vagina
Semen = mixture of sperm from vas deferens seminal vesicle fluid prostate fluid enters urethra which passes through the penis
Penis Three erectile bodies Two corpora cavernosa One corpus spongiosum surrounding urethra
Penis: Shaft Bulb or Root Glans Prepuce (foreskin)
Erection:
External Urethral Orifice (through Corpus Spongiousum) Urethra (through Prostate) Only at ejaculation Ejaculatory Duct Seminal Vesicles Ductus Deferens Constant Epididymis Efferent Ductules Rete Testis Tubulus Rectus Seminiferous tubules
Semen: Mixture of spermatozoa seminal vesicle fluid prostatic fluid Normal ejaculate: 4 – 6 ml 50 – 100 million sperm per ml Greatest in adolescence & young adults Decrease with age
Your assignment for tonight: Identify scrotum & testicles Identify location of epididymis, vas deferens, inguinal canal, prostate, seminal vesicles, urethra Identify corpora cavernosum & corpus spongeosum in both bulb and shaft of erect penis Observe clotting & liquification of freshly ejaculated semen