1. Unit 2 – Reproductive Module Histology of the male reproductive system
Safaa El Bialy (MD, PhD)

2. Objectives
Identify the following structures of the testes: seminiferous tubules, interstitial cells of Leydig, spermatogonia, primary spermatocytes, secondary spermatocytes, spermatozoa, Sertoli cells, epididymis (and its cell layers).
Describe the histology of the prostate.
Identify the erectile tissue in the penis.

3. Masculine genital apparatus
Four main functional constituents:
The testicles
Production of gametes
Secretion of testosterone
2. Duct system (efferent ducts, epididymis, vas deferens,
ejaculatory duct)
Receive, stock and vehicle the sperms
3. Exocrine glands (seminal vesicles and prostate)
Secrete a nutritive, lubricating liquid
4. Penis
Organ of copulation

4. 4

5. Testicular descent

6. Les couches du testicule
Epidermis
Dartos muscle
External spermatic fascia (fascia of external oblique muscle)
Cremasteric muscle (fibres of internal oblique muscle)
Internal spermatic fiascia(fascia transversalis)
Tunica vaginalis (parietal layer)
Virtual cavity formed by the 2 layers of the vaginalis
Tunica vaginalis (visceral layer)
Tunica albuginea
Interlobular septum of the testicle

8. Testis tunica vaginalis
sheath derived from the peritoneum that is picked up by the testis along the course of its migration to the scrotum
double mesothelial layer that covers almost the entire testis
tunica albuginea
capsule of connective tissue surrounding the testis
fibrous septa extend from the albuginea and divide the testis into lobules
lobuli testis
each lobule contains1-4 seminiferous tubules, where spermatozoa are produced
the seminiferous tubules converge towards a very anastomosed plexus, the rete testis; from there the efferent ducts carry spermatozoa to the epididymis
testicular interstitium (tissue surrounding the tubules) is formed by loose connective tissue containing vessels and interstitial cells of Leydig that secrete testosterone

9. Seminiferous tubules Structure of seminiferous tubules:
seminal epithelium rests on a basal lamina
epithelium made up of Sertoli cells (supporting cells, not germinal cells) and germinal cells at various stages of spermatogenesis
Basal membrane
Fibromyoblast
Fibrocyte
Sertoli cell
Spermatogonie A
Germinal cells at different stages
Spermatozoid
lumen

10. Seminiferous tubules and interstitium
Lumen
Basal lamina
Interstitial cells of Leydig
Spermatogonium
Sertoli cells
Spermatocyte I
Spermatids

11. Tubules séminifères SC sertoli cells PS primary spermatocytes
F fibroblasts
M myocytes
RS round spermatids
LS late spermatid

12. Cells of spermatogenesis
Spermatogonia
the only germinal cells present before puberty
round, sparse cytoplasm and found near the basal lamina
diploid for chromosome number (46, 2n)
Primary spermatocytes
largest germinal cells; abundant cytoplasm
large nucleus with chromatin strands in a reticular pattern
Secondary spermatocytes
produced by meiosis I
smaller and closer to the lumen
haploid for chromosome number (23, n)
divide quickly into spermatids, therefore rarely identified
Spermatids
produced by meiosis II
small with a dark nucleus; closest to the lumen
Spermatozoa
product of spermiogenesis
within the lumen
have long flagellum

13. Seminiferous tubules Lumen Spermatids Sertoli cells
Primary spermatocytes
Spermatogonia
Basal lamina 13

14. Sertoli cells Derived from mesoderm
They can only proliferate in the first year of life (their equivalent in the female are follicular cells)
They are long and pyramid shaped, and extend from the basal lamina to the lumen
They have an oval, indented, pale nucleus, and a clearly visible nucleolus

15. Seminal epithelium
Spermatozoa

16. Functions of Sertoli cells
Physical and nutritional support
Secretory functions
in the male embryo, they secrete MIS (Müllerian inhibiting substance), which inhibits the development of Müllerian ducts
secretion of ABP (Androgen Binding Protein), which concentrates testosterone in the tubular lumen for spermatogenesis and spermiogenesis
secretion of inhibin, which suppresses the pituitary secretion of FSH
secretion of tubular fluid necessary for transporting spermatozoa
Phagocytosis
Protection (blood-testis barrier)

17. Blood-testis barrier Tight junction complexes joining Sertoli cells
they are found above the spermatogonia and form the blood-testis barrier
Junctions that separate the seminiferous tubules into two compartments:
basal compartment
located between the basal lamina and tight junctions
contains spermatogonia, which have access to blood-borne materials
adluminal compartment
contains the other cells formed during spermatogenesis; they are protected by the blood-testis barrier
cells of this compartment are nourished by Sertoli cells
Following mitotic division of spermatogonia, the tight junctions break down to accommodate the passage of primary spermatocytes in the adluminal compartment, after which new tight junction complexes are formed

18. Interstitial cells of Leydig
Found between the seminiferous tubules
Abundant acidophilic cytoplasm containing lipid vacuoles; resemble adrenal cortical cells under the electron microscope (cells that synthesize steroids, therefore containing abundant smooth endoplasmic reticulum)
Secrete testosterone when stimulated by LH 18

19. Seminal fluid Sperm 3-5 ml per ejaculation
close to 100 million spermatozoa
approximately 20% are abnormally shaped and 25% are immobile
secretions of accessory glands
alkaline in order to neutralize the acid environment of the urethra and vagina
contains prostaglandin (affects the transport of spermatozoa in the genital systems of both sexes)
Sperm
Flagellum
Nucleus
Acrosome
Head

20. Epididymis Coiled shape has a head, body and tail
Formed from the epididymal canal
an extremely tortuous tube (about 4-6 m long!)
Surrounded by vascular connective tissue and smooth muscle for peristaltic movements
The epididymis is a reservoir for spermatozoa
maturation phase

21. Epididymis Epithelium pseudostratified columnar
Epididymal canal
Vascular connective tissue
Spermatozoa
Connective tissue
Epithelium
Spermatozoa
Smooth muscle
Stereocilia
Epithelium
pseudostratified columnar
cells have (stereocilia)

22. Spermatic cord and vas deferens
The vas deferens is the extension of the epididymal canal
It passes through the spermatic cord before entering the pelvis
The spermatic cord also contains blood vessels, nerves and connective tissue
Vas deferens
Adventitia
Muscle layer (thick)
Mucosa
Stellate lumen
Blood vessel
Connective tissue

23. Vas deferens Lumen Stereocilia Pseudostratified columnar epithelium
Lamina propria
Muscle layer

24. Canal deferent

25. Urethra is lubricated by:
Cowper’s bulbourethral glands
periurethral glands of Littre 25

26. Seminal vesicles
Glands that produce an alkaline viscous yellowish secretion (~ 70% of seminal fluid)
Mucosa is a system of anastomosed folds; formed by pseudostratified columnar epithelium and a lamina propria
Muscle layer formed by smooth muscle; contracts during ejaculation (inner circular and outer longitudinal)
Mucosal folds
Smooth muscle
Low magnification High magnification

27. Prostate
Gland that produces a thin milky secretion (30% of seminal fluid); rich in citric acid and hydrolytic enzymes
Formed by tubuloalveolar glands surrounded by fibromuscular stroma
3 prostate zones
transition – surrounds the proximal segment de of the prostatic urethra
central – surrounds the ejaculatory ducts
peripheral
Epithelium is simple columnar (mostly) or pseudostratified columnar

28. Prostate Glandular epithelium Gland Fibromuscular stroma Épithélium
Low magnification High magnification

29. Prostate Lumen Epithelium Corpora amylacea (prostatic concretions)
Fibromuscular tissue

30. Penis (cross section) 30

31. Erectile tissue in the penis
3 erectile tissues in the penis
2 corpora cavernosa and 1 corpus spongiosum
surrounded by tunica albuginea (connective tissue)
Erectile tissue is formed by wide vascular spaces bordered by endothelium, supported by trabeculae of connective tissue containing smooth muscle fibres
Trabecula
Vascular space
Tunica albuginea
Low magnification
High magnification

32. This table shows the male reproductive homologous structures to the women’s:
Female structure
Male structure
Labia majora
Scrotum
Bulbs of the vestibule
Corpora spongiosa
Subcutaneous smooth muscle of the labia majora
Dartos muscle of scrotum
Labia minora
Spongy urethra
Bartholin’s gland
Cowper’s gland
Crura
Crus of penis
Clitoris
Penis
Clitoral hood
Foreskin
Clitoral glans
Glans penis
Skene’s glands
Prostate gland
Ovary
Testis