Biology 212 Anatomy & Physiology I

1. Biology 212Anatomy & 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 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. Sustentacular Cells Testis or Testicle 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 Speciesspermatogenesis Human 64 Bull 54 Ram 49 Boar 34 Rat 48

17. Testis or Testicle Cellsbetween 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 Lateral 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 Tubulus Rectus Rete Testis 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