Male Reproductive System

Testis

Testis, epididymis, vas deferens, infant
Examine the specimen at low magnification and note the relationships of the testis, head of epididymis and vas deferens. Identify the thick dense regular connective tissue capsule surrounding the testis; this is the tunica albuginea. With higher magnification, note that it is covered by mesothelium, the visceral layer of the processus vaginalis. Identify the area of the mediastinum (thickened central extension of the tunica albuginea) which contains the rete testis (not well preserved in this specimen). Note also the muscular vas (ductus) deferens and the head of the epididymis on this specimen. This testis is from an infant, so the seminiferous tubules are not well developed.

Seminiferous Tubules

Testis, adult
Identify the thick dense irregular connective tissue capsule, the tunica albuginea, and the overlying mesothelium. Note the highly coiled structure of the seminiferous tubules seen in cross section. The cell-type population varies from tubule to tubule depending in the stage of the spermatogenic cycle. The endocrine testis consists of the Leydig cells which are found in clusters within the interstitial tissue between seminiferous tubules.
The exocrine testis consists of two cell types: the Sertoli cell and the germ cells. Identify the following germ cell types within the seminiferous tubules:
1.   Spermatogonia (most numerous cell type, adjacent to the basement membrane).
2.   Spermatocyte (twice the size of the spermatogonia, in two rows above spermatogonia, with distinctly clumped chromatin).
3.   Early spermatid (small cells adjoining the lumen, dark round nucleus).
4.   Late spermatid (small cells with dark condensed nucleus, the body embedded in apical portion of Sertoli cells, and tails protruding into lumen.
Also identify small eosinophilic residual bodies in the cytoplasm of Leydig cells.

Testis, human
Use this specimen to find Leydig cells in the connective tissue between seminiferous tubules. They are usually in clusters, their cytoplasm is eosinophilic, and they have the appearance of other steroid producing endocrine cells. These cells manufacture testosterone.
Identify Sertoli cells and the germ cells: spermatogonia, spermatocytes, early spermatids, and late spermatids. Identify residual bodies in the cytoplasm of Sertoli cells.

Rete Testis & Straight Tubules (tubuli recti)

Testis, human adult
Locate the mediastinum and examine the rete testis. The rete testis is composed of communicating channels between the straight tubules and efferent tubules (ductules). They are lined by simple cuboidal epithelium. No smooth muscle is present in this region.
Identify the straight tubules (tubuli recti) which connect the seminiferous tubules to the rete testis. They are lined by simple cuboidal epithelium.

Testis, human adult
Identify the mediastinum and the rete testis in of this testes specimen. The rete testis is lined by simple cuboidal epithelium.

Straight Tubules (tubuli recti)

Testis, human

Observe that straight tubules can also be observed in the connective tissue septa between seminiferous tubule

Ductus epididymis & efferent ductules

Epididymis, human
The efferent ductules have epithelia of variable height due to the presence of two populations of cells. The epithelium is composed of short principal cells with microvilli, and tall ciliated cells. The arrangement of short and tall cells gives the efferent ductules a scalloped appearance of the luminal margin. A thin circular layer of smooth muscle underlies the epithelium. The epithelial lining the ductus epidiymis is pseudostratified columnar epithelium with stereocilia. The epithelium is regular in height so that the luminal margin is even. The epithelial cells have stereocilia on their apical surface, which have an absorptive function. The ductus epididymis is a single tortuous duct with a thin layer of smooth muscle surrounding it.

Epididymis, monkey
Use this specimen to review the relative locations and appearance of the ductus epididymis and efferent ductules. The stereocilia of the ductus epididymis are better preserved in this specimen.

Ductus (vas) deferens & spermatic cord

Vas deferens
The vas deferens (ductus deferens) has a thick muscular wall and a narrow star-shaped lumen. The folding of the mucosa is an artifact of fixation due to the compression of the thick muscular wall. You should note that the smooth muscle is arranged in three layers; inner longitudinal, middle circular and outer longitudinal layer. The lining epithelium is pseudostratified columnar epithelium with stereocilia.

Vas deferens, human
The ductus deferens is better preserved in this specimen. Identify the three layers of the muscular wall; the inner longitudinal, middle circular and outer longitudinal layer. Observe the pseudostratified columnar epithelium with stereocilia lining of the lumen.

Spermatic cord
In the spermatic cord, there are bundles of nerve fibers, adipose tissue and blood vessels. Observe the skeletal muscle of the cremaster muscle in the scrotal wall. Note that the numerous veins (some with blood in the lumen) are atypical in that they resemble arteries and have two layers of smooth muscle: an inner circular layer and outer longitudinal layer. This is part of the pampiniform plexus of veins. Observe the muscular artery and compare to the veins. Note how the veins surround the artery; this is enables the cooler venous blood to cool arterial blood flowing to the testes. Identify the lymphatic vessels, which also have unusually thick muscular walls. Identify the ductus deferens and its three muscular walls.

Spermatic cord, human
Identify the ductus (vas) deferens, the muscular artery, and the veins of the pampiniform plexus in this specimen of the spermatic cord. Observe the inner circular layer of smooth muscle in the tunica media of the veins, and the outer longitudinal layer of smooth muscle in the tunica adventitia. Observe the prominent valves in one of the veins. Examine the presence of peripheral nerves and adipose tissue throughout the spermatic cord. Note that the artery is surrounded by the veins of the pampiniform plexus. The pseudostratified columnar epithelium with stereocilia lining the lumen of the ductus deferens is particularly well-preserved in this specimen.

Seminal vesicles

Seminal vesicle
Note the folding of the mucosa, the epithelium which can be a mixture of pseudostratified columnar or simple columnar, and the muscularis (an ill-defined inner circular and an outer longitudinal muscle coat). The apparently “isolated” profiles of the seminal vesicle epithelium actually represent sections through an elongated sac which is highly infolded and pass in an out of the plane of section.

Seminal vesicle
Note the vacuolated apical cytoplasm the epithelium which is characteristic of seminal vesicle epithelium. Observe the muscularis layer that surrounds the glandular epithelium profiles. The muscularis is has an inner longitudinal and inner circular layer of smooth muscle.

Prostate gland

Prostate gland and prostatic urethra
Note the prostatic glandular tissue with simple columnar to pseudostratified glandular epithelium. Note the fibromuscular stroma that surrounds the glands, which is composed of smooth muscle interspersed among the connective tissue.
Identify the prostatic urethra, which is lined by transitional epithelium. Observe the periurethral mucosal glands that empty into the prostatic urethra at several locations. Identify the periurethral submucosal glands, which are linked to the lumen of the urethra by a small number of short ducts at the urethral crest. The main prostatic glands are located more peripherally.

Prostate gland, older human
Lamellated prostatic concretions (corpora amylacea) accumulate with age in the lumen of the main prostatic glands.

Penis

Penis and penile urethra
Observe the paired corpora cavernosa of the penis and corpus spongiosum surrounding the penile urethra. The corpora cavernosa are surrounded by the tunica albuginea, which is composed of dense irregular connective tissue. Note that in this specimen, the penile urethra is lined by pseudostratified columnar epithelium, but that it will transition to stratified squamous epithelium in the distal penis. Identify the dorsal arteries, dorsal nerves and dorsal veins. Identify the central artery in the center of the corpora cavernosa. In the erectile tissue of the corpora cavernosum and spongiosum, there are numerous blood-filled venous spaces surrounded by connective tissue and slips of smooth muscle. Observe the helicine arteries, which are derived from the central arteries, and drain directly into the vascular spaces of the erectile tissue. Identify the mucous-secreting glands of Littre that empty into the penile urethra.