Download SSN Histology Male Reproduction

SSN Histology
Male Reproduction
Comments to Patrick McCormick ([email protected])
Seminiferous Tubules
1) Sertoli Cells (sustentacular cells)
a) function is to
i) create the blood-testis barrier
(1) isolates haploid germ cells from immune system
ii) secrete androgen binding protein (ABP)
(1) high concentration in lumen maintains high local testosterone
iii) support spermatids
iv) phagocytose residual bodies
b) large cells which extend from the basement membrane to the lumen
c) have prominent ovoid or triangular shaped nuclei
d) junctional complex between Sertoli cells
i) very tight junction (zonula occludens)
ii) flattened SER parallel to plasma membrane
iii) actin filament bundles between SER and plasma membrane
iv) gap junctions between Sertoli cells
e) Sertoli to spermatid junction
i) similar to S-S junction, but no tight junction
f) secretes inhibin
i) acts on AP to inhibit FSH release
g) secretes plasminogen activator
i) converts plasminogen to plasmin and transferrin
h) stimulated by FSH, testosterone
2) Leydig Cells
a) function: secrete testosterone
b) contain rod-shaped cytoplasmic crystals of Reinke
c) show 3 characteristics on EM (remember, they are steroid secreting cells!)
i) many lipid droplets
ii) abundant SER  eosinophilia under light
iii) tubulovesicular mitochondria
d) if the pointer is on a large cell in the interstitia, it's probably a Leydig cell
e) active early in life to 5 months, then inactive
i) hormones at puberty reactivate cells for life
f) stimulated by LH, prolactin (LH = Leydig)
3) Gametes
a) located between Sertoli Cells at different stages of development
b) spermatogonia sit on the basement membrane
c) any cell not touching the basement membrane = spermatocyte
d) more mature spermatocytes & spermatids are closer to the lumen
i) have smaller, denser nuclei
Spermatogenesis & Spermiogenesis
Cell Stage
spermatogonia (stem cells)
primary spermatocyte
secondary spermatocyte
spermatids
spermatozoa & residual bodies
Sperm Duct Pathway
Duct
Epithelium
Tubuli Recti
Simple cuboidal
Rete Testis
Simple cuboidal &
low columnar
Efferent Ductules Pseudostratified
columnar &
cuboidal
Epididymis Duct
Pseudostratified
columnar
Vas Deferens
Pseudostratified
columnar
Features
early: ovoid nuclei, may undergo mitosis
later: spherical nuclei, committed to differentiation,
all child cells linked by cytoplasmic bridges
post-synthesis; 4N, diploid
made by meiosis I; 2N, haploid (rarely seen)
made by meiosis II; 1N, haploid
Projections?
none
Some have a
single flagellum
Ciliated
Function
Fluid secretion
Fluid secretion
Stereocilia
Reabsorb fluid;
Sperm motility & maturation
Conduit
Some stereocilia
Reabsorb fluid secreted in the
seminiferous tubules
Interstitial cells
1) Efferent Ductules
a) immotile, immature sperm in lumen
b) epithelia has wavy sawtooth appearance due to variable cell heights
c) smooth muscle & elastic fibers
d) in head of epididymus
2) Epididymus
a) maturing motile sperm in lumen; decapacitation occurs
i) principal (tall) cells secrete glycoproteins and sialic acid
b) long stereocilia
c) smooth muscle; increases in thickness from head to tail (3 layers)
d) extensive Golgi apparatus, stains black with silver
i) secrete products for maturation of sperm
3) Vas Deferens
a) abundant smooth muscle in three layers: (blue on trichrome)
i) inner longitudinal
ii) middle circular
iii) outer longitudinal
b) cross-shaped opening in cross section
c) distal end forms ampulla  duct of seminal vesicle  ejaculatory duct
Seminal Vesicle
1) Structure
a) paired glands, highly folded lumen
b) non-ciliated
c) no smooth muscle in these folds
d) simple columnar or pseudostratified columnar epithelium, with basal cells
e) folded lumen surrounded by smooth muscle layer for ejaculation.
2) Secretions
a) secretes fructose, simple sugars, ascorbic acid, amino acids and prostaglandins
b) lumen filled with acidophilic secretory material
3) Not for sperm storage
Prostate Gland
1) Structure
a) surrounded by a fibroelastic capsule
b) incomplete septa divide prostate into lobules
c) parenchyma has tubulo-alveolar glands that secrete into the urethra on ejaculation
i) embedded in dense fibro-elastic connective tissue interlaced with smooth muscle
d) simple or pseudostratified columnar epithelium
2) innervated by sympathetic nervous system (Sympathetic = Shoot)
3) prostatic urethra = portion of urethra that passes through the prostate
a) has transitional epithelium lining
b) becomes (pseudo)stratified columnar distal to ejaculatory ducts
4) Secretes citric acid, acid phosphatase, and fibrinolysin (liquefies semen)
a) also serine protease (PSA), produced by liver
5) concretions (corpora amylacea) occur in the glandular lumens, increase with age
a) They are good markers!
Penile Cross Section
1) corpus spongiosum  ventral erectile tissue
a) surrounds penile urethra & deep arteries, forms glans
2) corpora cavernosa  dorsal erectile tissue, paired
a) sinuses are lined with vascular endothelium
3) tunica albuginea is a dense fibrous elastic layer surrounding erectile tissue
a) forms capsule of testis
4) penile urethra
a) stratified columnar/cuboidal epithelium.
b) glands of Littre are mucous secreting glands along lumen