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 7th & 8th weeks
Male Testes, penis, scrotum begin development Female Clitoris, labia begin 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 containing Cremaster Muscle (part of external
oblique muscle) Vas Deferens Testicular Nerve, Artery & Vein Plexus 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 Sustentacular Cells Testis or Testicle Spermatogonia Primary
Spermatocytes Secondary Spermatocytes Spermatids Sperm Testis or Testicle Cells between
groups of seminiferous = Interstitial tubules 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
Lateral 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: (through Corpus Spongiousum) Urethra
External Urethral Orifice (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
