Graduate Microanatomy, 1998
Graduate Microanatomy, 1998
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Reproductive System study guide Lab Exercises:
Date page was last edited 06/08/04 |
Lab Exercises: Testis Look at slide 72 which contains a section through the Testis and Epididymus. With the lowest power, identify the CREMASTERIC FASCIA outside the testis, containing skeletal muscle fibers. It is surrounded by connective tissue. Outside the muscle layer is the OUTER SPERMATIC FASCIA; inside the muscle fiber layer is the INNER SPERMATIC FASCIA. The next layer is an empty space. This is the cavity of the tunica vaginalis, derived from the embryonic processus vaginalis. Then, one encounters a layer of dense connective tissue called the TUNICA ALBUGINEA. It contains numerous large blood vessels. Inside the tunica albuginea one can find the numerous SEMINIFEROUS TUBULES. The following Figure shows, from left to right, the Tunica albuginea (with a blood vessel), the cavity of the tunica vaginalis, and some of the spermatic fascia.
Look at the middle of the section of the Testis where there is connective tissue radiating outward from the MEDIASTINUM TESTIS. These connective tissues septa divide the testis into wedge-shaped lobulues. The Mediastinum is dense connective tissue in the middle of the gland. It is distinguished by channels lined by low cuboidal epithelium called RETE TESTIS. The following sections show the Rete testes.
SEMINIFEROUS TUBULES Seminiferous tubules contain the SPERMATAZOA in various stages of development along with the SERTOLI CELLS. Each tubule profile may show particular developmental stages in a high concentration, because development tends to occur in waves down the tubules. After the sperm are produced they travel to the TUBULI RECTI (straight tubules) which are found in the septa radiating from the mediastinum. The tubuli recti connect the seminiferous tubules with the rete channels and tubules. The following photograph shows seminiferous tubules surrounding a connective tissue septum containing a tubulus rectus.
SERTOLI CELLS are distinguished by their location (near the border) and the shape of the nucleus. In the above photograph, note the outer layer of cells which are flattened and contractile (called MYOID CELLS). The Sertoli cell is identified by its triangular nucleus (kite-shaped). 1) What is the function of the Sertoli cell?
SPERMATOGONIA are also close to the basal lamina. They are large round cells with a pale-staining round or oval nucleus that is distinctly different from the nucleus of Sertoli cells. Sometimes you can see them in mitotic division. 2) Can you find a Sertoli cell in the above photograph? In the next rows, further away from the periphery, are either PRIMARY SPERMATOCYTES or SPERMATIDS. The Primary spermatocytes have a large floccular nucleus. They can be found in the following photograph.
Similar, but smaller secondary spermatocytes might be seen, however, because they complete meiosis II rapidly, you are more likely to see the smaller early spermatids. The early spermatid is small and round whereas the LATE SPERMATID is more conical. It may have a flagellum and a dense nucleus. The above photograph shows both primary spermatocytes and spermatids. Spermatids are shown also in the following photographs.
3) In the following photo, you should be able to find Sertoli cells, Primary spermatocytes, and spermatids. Identify an example of each.
LEYDIG CELLS The connective tissue in-between the tubules contains clusters of INTERSTITIAL CELLS (LEYDIG CELLS). They will be difficult to find in slide 72. You can, however, see them in slide 4. This slide does not have well preserved seminiferous tubules, however the Leydig cells are prominent. The following two sections illustrate them. They are round, acidophilic (pink) and may contain some vacuoles.
4) What is the function of the Leydig cell? What hormone does it secrete?
5) What hormone stimulates Leydig cells and where is that hormone secreted?
The following photograph shows a section through a fetal testis. From your studies above, you should be able to distinguish 6) Leydig cells and Seminiferous tubules.
7) In the seminiferous tubules, what is the most frequent cell type found? _______________________ What other cell type might be found and why?
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