Biology 211 Anatomy & Physiology I

Biology 211 Anatomy & Physiology I

Biology 212 Anatomy & Physiology 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 Both sexes: Gonads (ovaries & testes) remain inactive until puberty, when adenohypophysis (anterior pituitary) stimulates: production of gametes (sperm & oocytes)

secretion of gonadal hormones Reproductive System of Adult Male - Midsagittal Reproductive System of Adult Male Coronal from back Cremaster Muscle

(part of external oblique muscle) Scrotum Spermatic Cord

containing Vas Deferens Testicular Nerve, Artery & Vein Plexus Epididymis

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 by connective tissue Septa Testis or Testicle Each testis divided into approximately 250

Lobules Each lobule contains one to four coiled Seminiferous Tubules where Sperm are produced Testis or Testicle

Each lobule contains one to four coiled Seminiferous Tubules where Sperm are produced Testis or Testicle

Sustentacular Cells Testis or Testicle Spermatogonia Primary Spermatocytes

Secondary Spermatocytes Spermatids Sperm Testis or Testicle Sperm production (spermatogenesis) by seminiferous tubules under control of follicle stimulating hormone

produced by pituitary gland. Species Human Bull Ram Boar Rat

Days for completion of spermatogenesis 64 54 49 34

48 Testis or Testicle Cells between Interstitial seminiferous = cells tubules

Secrete testosterone under stimulation by luteinizing hormone (interstitial cell stimulating hormone) produced by pituitary gland

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 and are stored until ejaculation Debris also removed in epididymis Sperm from epididymis pass into vas deferens or ductus deferens which enters spermatic cord

Spermatic cord: Vas Deferens Testicular artery Testicular veins Autonomic nerves Cremaster muscle from external oblique

Tunica vaginalis extension of peritoneum All wrapped in External Spermatic Fascia Spermatic cord: Passes through inguinal canal into abdomen

Within abdomen, vas deferens passes to posterolateral side of bladder Lateral 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:

Parasympathetic stimuli cause arterioles in three erectile bodies (corpus spongiosum and corpora cavernosa) to dilate. The erectile bodies fill with blood and swell. This also presses on veins

of the penis, restricting blood flow out of the penis. Erection: Ejaculation: Physical stimulation of penis sends afferent nerve signals to

lumbar spinal cord. Reflexive efferent nerve signals: 1) Sympathetic, causing: Constriction of bladder sphincters Peristaltic contraction of epididymis, vas deferens, & ejaculatory ducts move sperm into urethra Contraction of seminal vesicles and prostate move their secretions into urethra

Ejaculation: Physical stimulation of penis sends afferent nerve signals to lumbar spinal cord. Reflexive efferent nerve signals: 2) Somatic, causing: Contraction of skeletal muscles along bulb of penis

force semen along urethra and out external urethral orifice External Urethral Orifice (through Corpus Spongiousum)

Urethra (through Prostate) 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

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