1. Biology 212 Anatomy & Physiology I
Male Reproductive System

2. Human Reproductive System:
- Begins developing in 4th week of embryonic development.
Remains “sexually indifferent”
until 7th week in male
8th week in female

4. Both sexes: Gonads (ovaries & testes) remain inactive until puberty, when adenohypophysis (anterior pituitary) stimulates: production of gametes (sperm & oocytes)
secretion of gonadal hormones

5. Reproductive System of Adult Male - Midsagittal

6. Reproductive System of Adult Male – Coronal from back

7. Cremaster
Muscle
(part of external
oblique muscle)
Scrotum

8. Spermatic Cord Vas Deferens Testicular Nerve, Artery & Vein Plexus
containing
Vas Deferens
Testicular
Nerve,
Artery &
Vein Plexus
Epididymis
Testis

9. 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

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

11. Testis or Testicle Each testis divided into approximately 250 Lobules
Each lobule contains
one to four coiled
Seminiferous Tubules
where
Sperm are produced

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

13. Testis or Testicle

14. Testis or Testicle Sustentacular Cells Spermatogonia
Primary Spermatocytes
Secondary Spermatocytes
Spermatids
Sperm

16. Testis or Testicle
Sperm production (spermatogenesis) by seminiferous tubules under control of follicle stimulating hormone produced by pituitary gland.
Days for
completion of
Species spermatogenesis
Human
Bull
Ram
Boar
Rat

17. Testis or Testicle
Cells between
seminiferous =
tubules
Interstitial
cells
Secrete testosterone under stimulation by luteinizing hormone (interstitial cell stimulating hormone) produced by pituitary gland

18. Testis or Testicle
Sperm pass from seminiferous tubule into
tubulus rectus

19. Testis or Testicle
Sperm pass from seminiferous tubule into
tubulus rectus
then into rete testis

20. Sperm pass from seminiferous tubule into
tubulus rectus
then into rete testis
through efferent ductules

21. Sperm pass from seminiferous tubule into
tubulus rectus
then into rete testis
through efferent ductules
to epididymis

22. 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

23. Sperm from epididymis pass into vas deferens or ductus deferens
which enters spermatic cord

24. 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

25. Spermatic cord:
Passes through inguinal canal into abdomen

26. Within abdomen, vas deferens passes to posterolateral side of bladder
View

27. Within abdomen are two accessory glands:
the seminal vesicles and the prostate
Posterior
View

28. Seminal Vesicles
Paired, posterior to bladder

29. Seminal Vesicles
Paired, posterior to bladder
Join with ampulla of vas deferens to form ejaculatory duct

30. 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

31. Prostate
Inferior to bladder
Surrounds ejaculatory ducts and proximal part of urethra

32. 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

33. Semen = mixture of sperm from vas deferens
seminal vesicle fluid
prostate fluid
enters urethra which passes through the penis

34. Penis
Three erectile bodies
Two corpora cavernosa
One corpus spongiosum
surrounding urethra

35. Penis:
Shaft
Bulb
or Root
Glans
Prepuce (foreskin)

36. 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.

37. Erection:

38. 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

39. 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

40. 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

41. 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

42. 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