BIOL 302 – Male Reproductive System
Double external layer: tunica vaginalis (parietal – outer; visceral – inner)
Capsule: tunica albuginea
Septa that emanate from this capsule (tunica albuginea) to subdivide the testis into
lobules. Lobules have seminiferous tubules surrounded by connective tissue that
The septa converge towards the midline of the posterior border, meeting along a
thickening of the tunica albuginea called the mediastinum testis.
Rete testes: network of delicate tubules located in the hilum of the testicle that
carries sperm from the seminiferous tubules to the efferent ducts.
Ductus efferentes: The efferent ducts connect the rete testis with the initial section
of the epididymis.
Epididymis: a highly convoluted duct behind the testis, along which sperm passes
to the vas deferens.
Vas deferens: the duct that conveys sperm from the testicle to the urethra. Seminiferous Tubule
Seminiferous tubules are located in the testes, and are the specific location of
meiosis, and the subsequent creation of gametes, namely spermatozoa. The
epithelium of the tubule consists of Sertoli cells, which are tall, columnar type
cells that line the tubule. In between the Sertoli cells are spermatogenic cells,
which differentiate through meiosis to sperm cells.
Site of spermatogenesis (production spermatozoa) and spermiogenesis
(maturation of spermatozoa). It is a peripheral to central maturation (new cells in
periphy and mature as they move to the centre).
Spermatogonia type A spermatogonia type B spermatocytes spermatids
o Spermatogonia Type A: On basement membrane, small round nuclei, fine
chromatin grains and one or two nucleoli. They are stem cells to divide to
form both type A and type B spermatogonia.
o Spermatogonia Type B: On basement membrane, pale cytoplasm, round
nuclei with chromatin granules of variable size which attach to nuclear
membrane and one nucleolus. They do not function as stem cells and
always form primary spermatocytes.
o Primary Spermatocytes: Large round pale nuclei, visible chromosomes,
middle of epithelium. They appear larger than spermatogonia. The
completion of the first meiotic division results in the formation of
o Secondary Spermatocytes: They are smaller than primary spermatocytes.
They rapidly enter and complete the second meiotic division and are
therefore seldom seen in histological preparations. Their division results in
the formation of spermatids.
o Spermatids: small round nuclei, not a lot of cytoplasm, close to lumen.
They are small with an initially very light (often eccentric) nucleus. The chromatin condenses during the maturation of the spermatids into
spermatozoa, and the nucleus becomes smaller and stains darker.
o Spermatozoa: elongated, condensed nuclei, no cytoplasm, close to lumen
Sertoli Cells: support and nutrition of germ cells. Tall cells in vertical orientation,
pale nuclei, prominent nucleolus, nuclei middle of epithelium
The seminiferous tubule is lined by a stratified epithelium, lined by a basal
membrane and covered by a sheath of connective tissue. The connective tissue
contains fibroblasts and myoid cells. The myoid cells are contractile, and produce
gentle peristaltic waves in the tubules.
The Sertoli cells have pale nuclei and dense nucleoli. The spermatogonia and the
nuclei of the Sertoli cells lie on the basal membrane. The nuclei of these cells are
pale, with prominent nucleoli.
Primary spermatocytes, secondary spermatocytes, spermatids and spermatozoa
are in the adluminal compartment.
The lumen also contains some spermatozoa, and cellular debris. Leydig cells: located in the interstitial tissue between the convoluted seminiferous
tubules, they surround blood and lymph vessels. They constitute the endocrine
component of the testis. They synthesize and secrete testosterone. They are
vacuolated and have have smooth ER and Golgi bodies. Leydig cells occur in
clusters, which are variable in size and richly supplied by capillaries. The
cytoplasm is strongly acidophilic and finely granular. The nucleus is large, round
and often located eccentric in the cell. Tubes and Ducts
Ductus deferens (vas deferens)
Move sperm from testes to exterior for ejaculation
Add fluids to ejaculate
Basic structure of all tubes and ducts:
Mucosa: pseudostratified epithelium, lamina propria
Muscularis externae: smooth muscle
Function: Collect sperm from semiferous tubules; spermatozoa pass through the
rete testes to the ductili efferentes
Mucosa: simple cuboidal/low columnar epithelium
Looks like trabecular bone Ductuli Efferentes
Function: resorption of fluids from seminiferous tubules
Mucosa: cuboidal/columnar epithelium – columnar are ciliated, cuboidal are
absorptive – the two cell heights give a wavy appearance
Leave the retes testes and open into the epididymis
Muscularis externae: layer of smooth muscle
Connective tissue around smooth muscle Epididymis
Highly convoluted tubules
Function: maturation of sperm (gain motility and ability to fertilize), store sperm
Mucosa: pseudostratified epithelium with stereocilia, lumen has sperm
Muscularis externae: smooth muscle
Connects the epididymis (where sperm is matured) to the urethra (where sperm is
ejaculated). It is a muscular tube that propels the sperm to the urethra through
peristalsis contractions where it exits the body.
Mucosa: pseudostratified epithelium with stereocilia, lamina propria Muscularis externae: three layers of smooth muscle (longitudinal, circular,
Small lumen compared to layers of smooth muscle
Accessory Reproductive Glands
Function: secrete a slightly alkaline fluid, milky or white in app