1. The Male Reproductive System

2. The Male Reproductive System

3. The Male Reproductive System Main Topics
General Information
Testis
Ducts
Accessory Sex Glands
Penis
Supporting Ligaments
Male Reproductive Physiology

4. Testis Overview
Connective Tissue Coverings (tunica vaginalis; tunica albuginea) & supporting structures (scrotum)
Seminiferous Tubules – site of sperm production

5. Ducts Overview Ducts of the Testis Ducts of the Epididymis
Ductus Deferens (vas deferens; seminal duct)
Ejaculatory ducts
Urethra

6. Accessory Sex Glands Overview
Seminal Vesicles
Prostate Gland
Bulbourethral Glands (Cowper’s glands)

7. The Penis Overview
Body
Root
Glans Penis

8. Male Reproductive Physiology Overview
Erection
Emission
Ejaculation

9. General Information Gonads (testes; ovaries) Ducts
production of gametes (sperm; secondary oocytes); secrete hormones
Ducts
transport and store gametes
Accessory sex glands
produce materials that support gametes
Supporting structures – penis; uterus

10. Testis
Connective Tissue Coverings (tunica vaginalis; tunica albuginea) & supporting structures (scrotum)
Seminiferous Tubules – site of sperm production

11. The Testis

12. The Testis Connective Tissue Coverings
Tunica vaginalis
outer, serous membrane that partially covers the testis
Tunica albuginea
inner, dense fibrous capsule
extends inward forming septa that divide each testis into internal compartments (lobules)
lobules compartments within the testis; each contains 1-3 tightly coiled tubules (seminiferous tubules) packed in an areolar connective tissue

13. The Testis Connective Tissue Coverings
Scrotum
connective tissue sac that supports the testes
contains skeletal muscle (cremaster) and smooth muscle (dartos) which regulate the temperature of the testes by controlling the distance between the testes and the body

14. The Testis Seminiferous Tubules
dead-ended, coiled tubules
outer basement membrane layer
inner lumen which empties into the straight tubules
site of sperm production (spermatogenesis)

15. Seminiferous Tubules

16. Meiosis

17. Seminiferous Tubules Spermatogenic cells
Spermatogenic cells - sperm-forming cells; successive layers of developing cells, from most immature (next to basement membrane) to most mature (next to lumen
spermatogonia diploid (2n) stem cells that develop from primordial germ cells; lie dormant until puberty; lie next to basement membrane
primary spermatocytes - differentiated (more mature) diploid daughter cells of spermatogonia mitosis
secondary spermatocytes - haploid (n) daughter cells of primary spermatocytes which have undergone reduction division (meiosis I)
spermatids - haploid daughter cells of secondary spermatocytes which have undergone equatorial division (meiosis II); lie close to lumen; each diploid primary spermatocyte produces four haploid spermatids
sperm (spermatozoa)

18. Spermatogenic cells

19. Sperm maturation of spermatids (spermiogenesis)
mature at rate of about 300 million per day
once ejaculated, have about a 48 hour survival time within the female reproductive tract

20. Sperm head mid-piece tail
contains DNA and acrosome (lysosome-like structure that aids in the penetration of the secondary oocyte)
mid-piece
contains numerous mitochondria that supply ATP for locomotion
tail
flagellum; propels the sperm cell

21. The Seminiferous Tubules Sustentacular cells (Sertoli cells)
extend from the basement membrane to the lumen of the tubule
spermatogenic cells are embedded within the Sertoli cells
basal surface forms tight junctions with neighboring cells
forms a blood-testis barrier

22. Sustentacular cells (Sertoli cells) Functions
support, protect, & nourish developing spermatogenic cells
phagocytize excess spermatid cytoplasm
mediate effects of testosterone and FSH
control movements of spermatogenic cells
control release of sperm into the lumen
produce fluid for sperm transport
secretes hormone, inhibin, which helps regulate sperm production by inhibiting secretion of FSH from the anterior pituitary gland

23. Sustentacular Cells

24. The Seminiferous Tubules Interstitial endocrinocytes (Leydig cells)
fill spaces between adjacent seminiferous tubules
secrete testosterone

25. Interstitial Endocrinocytes (Leydig cells)

26. Ducts Ducts of the Testis Ducts of the Epididymis
Ductus Deferens (vas deferens; seminal duct)
Ejaculatory ducts
Urethra

27. Ducts of the Testis Straight tubule Rete testis
single, simple columnar-lined, short, straight tubule
collects sperm (& seminiferous fluid) from the seminiferous tubules of the lobule
empties into the rete testis
Rete testis
network of anastomosing channels
lined with simple squamous to simple cuboidal epithelium
collects sperm from the straight tubules of all the lobules

28. Epidiymis
comma-shaped organ lying along the posterior surface of the testis
consists of a:
head (mainly efferent ducts)
body (ductus epididymis)
tail (ductus epididymis)

29. Ducts of the Epididymis
Efferent ducts
10-15 coiled tubules that drain the rete testis
forms the head of the epididymis
empties into the ductus epididymis
Ductus epididymis
tightly coiled (20 ft. in uncoiled length) tubule
lined by pseudostratified columnar epithelium encircled by smooth muscle layers
comprises the body & tail of the epididymis
collects sperm from the efferent ducts
empties into the vas deferens

30. Ductus Deferens (vas deferens; seminal duct)
18” long
lined by pseudostratified columnar epithelium
ascends along the posterior border of the epididymis, through the inguinal canal, over the ureter
descends retroperitoneally behind the bladder toward the urethra
Ampulla of ductus deferens
dilated, terminal segment of the vas deferens
joins the excretory duct of the seminal vesicle to form the ejaculatory duct

31. Vas Deferens Functions
stores sperm (up to several months)
conveys sperm from epididymis toward the urethra by peristaltic contractions of its smooth muscular layers (inner & outer longitudinal; middle circular)

32. Ejaculatory Ducts 1” long
formed by the union of the duct from the seminal vesicle and the ampulla of the vas deferens
forcibly ejects sperm into the prostatic urethra (it pierces the prostate gland) just before ejaculation (expulsion of semen from the urethra)

33. Urethra passageway for semen through the prostatic urethra
through the membranous urethra
through the spongy urethra
through the external urethral orifice

34. Accessory Sex Glands Overview
Seminal Vesicles
Prostate Gland
Bulbourethral Glands (Cowper’s glands)

35. Semen & Seminal Fluid Semen Seminal fluid
slightly alkaline mixture of sperm and seminal fluid
provides sperm with a transportation medium and nutrients
neutralizes hostile acidic environment of male urethra and female vagina
Seminal fluid
liquid portion of semen that consists of the secretions of the seminiferous tubules, seminal vesicles, prostate gland, and bulbourethral glands

36. Seminal Vesicles paired, convoluted, pouch-like structures
2” in length
lie posterior to and at the base of the bladder
Secretions
alkaline, viscous fluid
contains fructose (for ATP production by sperm), prostaglandins (contribute to sperm motility & viability), semenogelin (protein coagulator of ejaculated semen)
60% of seminal volume

37. Prostate Gland single, doughnut-shaped gland
surrounds the prostatic urethra
prostatic secretions enter prostatic urethra through many prostatic ducts
Secretions
milky, slightly acidic fluid
contains citrate (for ATP production by sperm)
acid phosphatase
proteolytic enzymes [prostate-specific antigen (PSA); pepsinogen; lysozyme] which liquefy coagulated semen
25% of seminal volume

38. Bulbourethral Glands (Cowper’s glands)
paired, pea-sized glands
lie on either side of the membranous urethra within the urogenital diaphragm
ducts open into the spongy urethra
Secretions
during sexual arousal, secrete alkaline substance (neutralizes acidic environment of urethra) and mucus (for lubrication)

39. The Penis
Body
Root
Glans Penis

40. The Penis Body
Body- composed of three cylindrical masses of erectile tissue; permeated by blood sinuses; each bound by fibrous tissue (tunica albuginea)
Corpora cavernosa penis (sing: corpus cavernosum penis) - paired, dorsolateral masses; tapered ends (crura) are attached to the pelvis
Corpus spongiosum penis - mid-ventral mass; contains the spongy urethra

41. The Penis Root
Root - consists of the bulb of the penis and the crura of the penis
Bulb of the penis - expanded portion of the base of the corpus spongiosum penis; attached to the inferior surface of the urogenital diaphragm; enclosed by the bulbospongiosus muscle
Crura (sing: crus) - the tapered ends of the corpora cavernosa penis; attached to the ischial ramus and the inferior pubic ramus; surrounded by the ischiocavernosus muscle

42. The Penis Glans Penis
Glans Penis - distal end of the corpus spongiosum penis
Corona - margin of the glans penis
External urethral orifice - an enlarged, terminal, slit-like opening
Prepuce (foreskin) - loose covering over the glans penis

43. Male Reproductive Physiology
Erection
Emission
Ejaculation

44. Male Reproductive Physiology Erection
Erection - results from vascular changes
Parasympathetic nerve stimulation causes the arteries that supply the penis to dilate allowing large amounts of blood to enter the blood sinuses of the erectile tissue
The blood-filled spaces expand compressing the superficial veins that drain the penis and allowing more blood to trapped in the spaces
The erectile tissue becomes larger and stiffer

45. Male Reproductive Physiology Emission
the discharge of a small volume of semen before ejaculation
due to peristaltic contractions (in the ampulla of the vas deferens, the seminal vesicles, the ejaculatory ducts, and the prostate gland) which propels semen into the spongy urethra

46. Male Reproductive Physiology Ejaculation
Ejaculation - sympathetic nerve stimulation (Ll, L2) causes rhythmic simultaneous muscular contractions of the bulbospongiosus, the ischiocavernosus, and the anal sphincter; propels semen out of the external urethral orifice
Simultaneous contraction of the internal urethral sphincter prevents urine leakage from the bladder and semen from entering the bladder

47. Male Reproductive Physiology