Reading: RR&K Chapter 21
SLIDE 94d monkey testis (H&E)
(RR&K p667, Fig. 1,2)
This plastic embedded specimen shows a number of seminiferous tubules but does not include the capsule of the organ. Note the variation in shape, the many cross-sectional profiles, as well as the more elongate and irregular contoured profiles of the tubules. Select several cross-sectional profiles and compare the nuclear morphology of the germinal cells that constitute the tubular wall. Identify spermatogonia, spermatocytes and the early and late spermatids. The spermatogonia are cuboidal cells located at the base of the seminiferous epithelium. Above the spermatogonia layer, you see a heterogenous population of large cuboidal cells whose nuclei consist of condensed chromatin. These cells are spermatocytes which are in prophase I of meiosis. Early spermatids are smaller cells with distinct round nuclei and prominent nucleoli found near the lumen of the tubule. Late spermatids are identified by their highly condensed nuclei and the presence of a flagellum. Spermatids are associated with the epithelium. Those released into the lumen are referred to as spermatozoa. Residual bodies can also be found. Where do the residual bodies arise from? The cells that support the development of sperm are the Sertoli cells. These cells are tall columnar cells with large oblong nucleus oriented perpendicular to the basement membrane. They are relatively pale-staining and in most cases exhibit a prominent dark-staining nucleolus. Before leaving this slide, also examine the interstitial and peritubular tissue. The myoid (peritubular contractile) cells exhibit elongated nuclei and are situated just outside the basement membrane of the seminiferous epithelium. Outside the myoid cells are endothelial cells which line the extensive lymph network around the seminiferous tubules. The Leydig cells are relatively sparse in number, but they can be identified by their round nuclei and the presence of cytoplasmic vacuoles. What are these vacuoles?
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SLIDE 94e testis and epididymis, mouse (H&E)
(RR&K p671, Fig. 1,2)
This specimen has two small oval blocks of tissue, the testis and epididymis. The testis includes a portion of the tunica albuginea and good examples of seminiferous tubules and interstitial areas. Identify the thick connective tissue capsule of the testis called, the tunica albuginea. Within the seminiferous epithelium, identify the cells of spermatogenesis: spermatogoniae, spermatocytes, and early and late spermatids. Also identify Sertoli cells and residual bodies. What is the relationship between the Sertoli cell and the residual body? Examine the interstitial areas, particularly those that are in close proximity to the capsule. The lymphatic channels with pink staining lymph are clearly demarcated. Within these spaces are aggregates of Leydig cells which exhibit a vacuolated cytoplasm. The vacuoles probably result from extraction of the lipids stored as precursors for testosterone. Also present are the blood vessels which can be readily recognized by the presence of red blood cells. Distinguish between the single layer of myoid cells and the lymphatic endothelial cells. The smaller oval structure on your slide is the epididymis containing profiles of ductus epididymis. Identify the pseudo-stratified columnar epithelium within stereocilia that line the epididymis and note the prominent negative Golgi present in the taller cells.
Most tubules show spermatozoa present in their lumen. Some sections contain profiles of ductuli efferentes close by the epididymis. The epithelium of these tubules consist of tall and short columnar cells giving the lumen a Astar@ shaped appearance. The tall columnar cells have cilia and associated basal bodies, unlike the stereocilia of the epididymis.
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SLIDE 94c rete testis, human (H&E)
(RR&K p669, Fig. 2,3)
This section of the testis was cut through the mediastinum testis. Locate the seminiferous tubules and the rete testis. The junction of the seminiferous tubule with the tubuli recti (straight tubules) may be seen in certain favorable sections. The tubuli recti can be identified by locating the termination of the seminiferous epithelium. The continuation of the tubule is a short segment lined solely by Sertoli cells. The short tubuli recti join almost immediately with the rete testis. The rete has a simple cuboidal epithelium and an irregular lumen because it is composed of a network of interconnecting cavities.Review the seminiferous epithelium on this slide. Note, that the arrangement of cells in the seminiferous epithelium is quite different than on the previous two slides. Identification of the cell types within the seminiferous tubule is difficult and not advised. Examine the myoid and Leydig cells of the peritubular tissue. Can you see any ductuli efferentes on your slide?
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SLIDE 98a prostate and prostatic urethra, human (H&E)
(RR&K p675, Fig. 1,2,3,4)
This section of the central portion of the prostate gland includes prostatic urethra lined by transitional epithelium. On some of the slides the seminal colliculus is present with openings to the ejaculatory ducts. The prostate is easily identified by the presence of prostatic concretions within the lumen of the prostatic glands. These unusual stones frequently show growth rings, somewhat reminiscent of the annual growth rings seen in woody trees. Identify the pseudostratified epithelium of the prostatic glands and the thick fibromuscular stroma consisting of dense irregular connective tissue and smooth muscle bundles.
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SLIDE 97a seminal vesicle, human (H&E)
(RR&K p676, Fig. 1,2)
The seminal vesicle has a very different morphology as compared to the prostate. The lumen of the gland is expanded and the pseudostratified columnar epithelium frequently gives the appearance of being branched. This appearance is due to the folds in the epithelium rather than to actual branching. Underlying the epithelium is the lamina propria consisting of loose connective tissue. A prominent muscular wall is arranged into an inner circular layer and an outer longitudinal layer of smooth muscle.
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SLIDE 78a, penis, human (Masson)
(RR&K p665, Fig. 21.30)
The penis consists of two corpora cavernosa, and a corpus spongiosum which surrounds the spongy part of the urethra. Your slide contains the section of the ventral part of the penis which includes the section of the urethra.
Identify the urethra and classify the epithelium. The two corpora cavernosa and the corpus spongiosum are composed of erectile tissue and are bound together by a dense fibroelastic layer of tunica albuginea. Erectile tissue contains connective tissue and smooth muscle in which there are many vascular spaces lined by endothelial cells. , Helicine arteries located within the erectile tissue with unusually thick walls (mainly due to the presents of intimal cushions of smooth muscles and connective tissue) are difficult to identify.
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SLIDE 98p Prostate gland, adenocarcinoma (H&E)
(RR&K p675, Fig. 1,2,3,4)
The carcinoma of the prostate gland is the most common form of cancer in males (followed closely by lung cancer). Histologically, almost all tumors develop from the glandular epithelium of the prostate gland and therefore are classified as adenocarcinomas.
This section of the prostate has a dense connective tissue capsule. The capsule contains numerous nerves and blood vessels. Look for normal regions of prostate glandular tissue. The glands (with their prostatic concretions) are well separated by extensive fibromuscular stroma. In the regions of adenocarcinoma, you will find glands with a relatively normal, uniform epithelium consisting of simple cuboidal or low columnar cells. Usually the tumor is well differentiated with only few mitotic figures. However, the glands or malignant acini are numerous, smaller and closely spaced "back-to-back", with little or no intervening fibromuscular stroma. In addition, these acini can be found in very close apposition to nerves and to the epithelial walls of capillaries and small vessels. The invasion of the connective tissue by cancer cells surrounding nerves or vessels is a good indicator of malignancy. Do you see any lymphatic reaction to the tumor?
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The male reproductive system consists of both internal and external structures. These include: testis, epididymides, genital ducts, and penis, as well as accessory glands which include the seminal vesicles, prostate, and bulbourethral glands. This unit examines the structure of these organs, as well as the developmental stages of the spermatocyte.