The male reproductive system consists of testes that produce sperm through spermatogenesis in seminiferous tubules. Sperm exit the testes and travel through the epididymis, vas deferens, and urethra. Accessory glands including the seminal vesicles and prostate gland secrete fluids that combine with sperm to form semen. The testes are located in the scrotum to maintain a temperature slightly lower than body temperature, which is vital for sperm production.

1. Histology of the
Male Reproductive System

2. Introduction
• The male reproductive system consists of a pair of testes,
numerous ducts, and different accessory glands that produce
a variety of secretions that are added to sperm to form
semen.

4. • The testes contain spermatogenic stem cells eventually
transformed into spermatozoa, or sperm.
• From the testes, the sperm move through excurrent ducts to
the epididymis for storage and maturation.
• Sperm leave the epididymis via the ductus (vas) deferens and
exit the reproductive system through the penile urethra.

5. The scrotum
• The paired testes are located outside the body cavity in the
scrotum.
• In the scrotum, the temperature of the testes is about 2° to
3°C lower than normal body temperature.
• This lower temperature is vital for normal functioning of the
testes and spermatogenesis, or sperm production.

6. Layers of the Scrotum
• The scrotal wall is composed of the following structures from
the superficial to the deep layers:
• Skin, superficial fascia, dartos fascia, external spermatic
fascia, cremasteric fascia, and internal spermatic fascia.
• It varies from 2 to 8 mm in thickness.

9. Testes
• A thick connective tissue capsule, the tunica albuginea,
surrounds each testis.
• Posteriorly, the tunica albuginea thickens and extends inward
into each testis to form the mediastinum testis.

10. • A thin connective tissue septum extends from the
mediastinum testis and subdivides each testis into about 250
incomplete compartments or testicular lobules, each
containing one to four coiled seminiferous tubules.
• Each seminiferous tubule is lined by stratified germinal
epithelium, containing proliferating spermatogenic (germ)
cells and nonproliferating supporting (sustentacular) or
Sertoli cells.

11. Seminiferous tubules

12. • In the seminiferous tubules, spermatogenic cells divide, mature,
and are transformed into sperm.
• Surrounding each seminiferous tubule are fibroblasts, muscle like
cells, nerves, blood vessels, and lymphatic vessels.
• In addition, between the seminiferous tubules are clusters of
epithelioid cells, the interstitial cells (of Leydig).
• These cells are steroid-secreting cells that produce the male sex
hormone testosterone.

13. spermatogenesis
• The process of sperm formation is called spermatogenesis.
• This includes mitotic divisions of spermatogenic cells, which
produce replacement stem cells and other spermatogenic
cells that eventually give rise to primary spermatocytes and
secondary spermatocytes.

14. • Both primary and secondary spermatocytes undergo meiotic
divisions that reduce the number of chromosomes and the
amount of DNA.
• Division of secondary spermatocytes produces cells called
spermatids that contain 23 single chromosomes (22X or
22Y).
• Spermatids do not undergo any further divisions, but instead
are transformed into sperm by a process called
spermiogenesis.

15. • Once the spermatogenic cells in the germinal epithelium
differentiate, they are held together by intercellular bridges
during further differentiation and development.
• The intercellular bridges are broken when the developed
spermatids are released into the seminiferous tubules as
mature sperm.

16. Seminiferous tubule

17. Spermiogenesis
• Morphologic transformation of spermatid into sperm
• Size and shape of spermatid altered, with condensation of
nuclear chromatin
• On the anterior side, acrosome granules in vesicles spread
over the condensing nucleus as acrosome

18. • The acrosome contains hydrolytic enzymes needed to penetrate
cells that surround the oocyte
• On the posterior side, flagellum (tail) forms with mitochondria
aggregating at middle piece of sperm
• Residual cytoplasm is shed from the spermatids and
phagocytosed by Sertoli cells
• Mature sperm consists of a head, neck, middle piece, and
principal piece

19. Excurrent ducts
• Newly released sperm pass from the seminiferous tubules
into the intertesticular excurrent ducts that connect each
testis with the overlying epididymis.
• These excurrent ducts consist of the straight tubules (tubuli
recti) and the rete testis, the epithelial-lined spaces in the
mediastinum testis.

20. • From the rete testis, the sperm enter the ductuli efferentes
(efferent ducts), which conduct sperm from the rete testis to
the initial segment or the head of the epididymis.
• Epithelium of efferent ducts is uneven owing to ciliated and
nonciliated cells in the lumina
• Cilia in efferent ducts move sperm and fluid from seminiferous
tubules to ductus epididymis
• Nonciliated cells absorb much of the testicular fluid as it passes
to ductus epididymis

21. Straight tubules, rete testes and efferent ductules

22. • The extra-testicular duct that conducts the sperm to the
penile urethra is the ductus epididymis, which is continuous
with the ductus (vas) deferens and ejaculatory ducts in the
prostate gland.
• During sexual excitation and ejaculation, strong contractions
of the smooth muscle around efferent ducts, ductus
epididymis, and vas deferens expel the sperm.

23. • Pseudostratified epithelium with principal and basal cells lines
efferent ducts and epididymis
• Stereocilia line the surface of cells in ductus epididymis and vas
deferens
• Stereocilia absorb testicular fluid and the principal cells
phagocytose residual cytoplasm
• Principal cells in ductus epididymis also produce glycoprotein
that inhibits sperm capacitation

24. Epididymis

25. Epididymis

26. Ductus Deferens

27. Ampulla of the Ductus Deferens

28. Sertoli cells
• Offer Physical support, protection, nutrition, and release the
mature sperm into tubules
• Phagocytose residual cytoplasm of spermatids
• Secrete Androgen Binding protein (ABP) to concentrate
testosterone in tubules and testicular fluid for sperm
transport
• Secrete hormone inhibin and anti-müllerian hormone

29. Blood testes barrier
• Formed by tight junctions of adjacent Sertoli cells
• Separates seminiferous tubules and adluminal
compartments
• Protects developing sperm from autoimmune response and
harmful materials

30. Seminal vesicles
• Located posterior to the bladder and superior to prostate
gland
• Excretory ducts join with the ampulla of vas deferens to form
ejaculatory ducts
• Ejaculatory ducts continue through prostate gland to open
into prostatic urethra

31. • Produce fluid with sperm-activating fructose, the main
energy source for sperm motility
• Produce most of the fluid found in semen
• The seminal vesicle exhibits highly convoluted and irregular
lumina.
• A cross section through the gland illustrates the complexity
of the primary mucosal folds.

32. • These folds branch into numerous secondary mucosal folds,
which frequently anastomose and form irregular cavities,
chambers, or mucosal crypts.
• The lamina propria projects into and forms the core of the
larger primary folds and the smaller secondary folds.
• The folds extend far into the lumen of the seminal vesicle.

33. • The glandular epithelium of the seminal vesicles varies in
appearance, but is usually low pseudostratified and low
columnar or cuboidal.
• The muscularis consists of an inner circular muscle layer and
an outer longitudinal muscle layer.

34. • This arrangement of the smooth muscles is often difficult to
observe because of the complex folding of the mucosa.
• The adventitia surrounds the muscularis and blends with the
connective tissue.

35. Seminal vesicle

36. Prostate gland
• Located inferior to the neck of the bladder
• Urethra exits bladder and passes through prostate as
prostatic urethra
• Excretory ducts from prostatic glands enter the prostatic
urethra

37. • Transitional epithelium lines the prostatic urethra
• The gland is characterized by fibromuscular stroma and
prostatic concretions in the glands
• Small branched tubular prostatic glands produce watery
secretions with numerous chemicals, including prostate-
specific antigen

38. Prostate Gland

39. • Some of the prostatic glands contain solid secretory
aggregations called prostatic concretions (corpora amylacea)
in their acini.
• The prostatic concretions are characteristic features of the
prostate gland acini.
• The number of prostatic concretions increases with the age
of the individual, and they may become calcified.

40. Prostate Gland

41. Prostate Gland

42. • A longitudinal urethral crest of dense fibromuscular stroma without
glands widens in the prostatic urethra to form a smooth domelike
structure called the colliculus seminalis.
• The colliculus seminalis protrudes into and gives the prostatic urethra
a crescent shape.
• On each side of the colliculus seminalis are the prostatic sinuses.
• Most excretory ducts of prostatic glands open into the prostatic
sinuses

43. • In the middle of the colliculus seminalis is a blind tube called the
utricle.
• Also, two ejaculatory ducts open at the colliculus, one on each side of
the utricle

44. • The size of the glandular acini in the prostate gland is highly
variable.
• The lumina of the acini are normally wide and typically
irregular because of the protrusion of the epithelium
covered connective tissue folds.
• Some of the glandular acini contain proteinaceous prostatic
secretions.

45. • The glandular epithelium is usually simple columnar or
pseudostratified, however, there is considerable variation.
• In some regions, the epithelium may be squamous or
cuboidal.
• The excretory ducts of the prostatic glands may often
resemble the glandular acini.

46. • In the terminal portions of the ducts, the epithelium is
usually columnar and stains darker before entering the
urethra.
• The fibromuscular stroma is another characteristic feature of
the prostate gland.
• Smooth muscle bundles and the connective tissue fibers
blend together in the stroma and are distributed throughout
the gland.

47. Prostate Gland

48. Bulbourethral glands
• Small glands located at root of penis and in skeletal muscle
of urogenital diaphragm
• Excretory ducts enter the proximal part of penile urethra
• Produce mucous like secretion that serves as lubricant for
penile urethra

49. • The paired bulbourethral glands are compound tubuloacinar
glands.
• The fibroelastic capsule that surrounds these glands contains
connective tissue, smooth muscle fibers, and skeletal muscle
fibers.
• Because the bulbourethral glands are located in the
urogenital diaphragm, the skeletal muscle fibers from the
diaphragm are present in the glands.

50. Bulbourethral Gland

51. • Connective tissue septa from the capsule divide the gland
into several lobules.
• The secretory units vary in structure and size and resemble
mucous glands.
• The glands exhibit either acinar secretory units or tubular
secretory units.

52. • The secretory cells are cuboidal, low columnar or squamous,
and light staining.
• The height of the epithelial cells depends on the functional
state of the gland.
• The secretory product of the bulbourethral glands is
primarily mucus

53. penis
• Consists of erectile tissue and vascular spaces lined by
endothelium.
• Erectile corpora cavernosa is located on dorsal side and corpus
spongiosum on ventral side
• Tunica albuginea surrounds the erectile bodies
• Dorsal artery and deep artery supply erectile bodies with blood

54. • All three cavernous bodies are surrounded by loose
connective tissue called the deep penile (Buck’s) fascia
• It is in turn, surrounded by the connective tissue of the
dermis located below the stratified squamous keratinized
epithelium of the epidermis.
• Strands of smooth muscle of the dartos tunic, nerves,
sebaceous glands, and peripheral blood vessels are located
in the dermis

55. Penis

56. Penile Urethra

57. Clinical application
• Benign prostatic hyperplasia
• Prostatic cancer
• 70-80% occur in the peripheral zone
• 10-20% in the transitional zone
• 2.5% in the central zone
• Very rarely in the anterior zone

59. End…