Figure 2116

Schematic drawing of the Sertoli cell and its relationship to adjacent spermato-genic cells. This drawing shows the Ser-toli—to—Sertoli junctional specialization between adjacent Sertoli cells and the Sertoli-to-spermatid junctional specialization between the Sertoli cell and late spermatids. The Sertoli-to-Sertoli junctional complex is an adhesion device that includes a tight junction that contributes to the blood-testis barrier. The junctional specialization between the Sertoli cell and late spermatids residing in deep recesses within the apical cytoplasm is an adhesion device only. Lateral processes of the Sertoli cells extend over the surface of the spermatocytes and spermatids. Note the ultra-structural features of the Sertoli cell, including the microtubule arrays and characteristic shape of the nucleus and its karyosome. (From Bloom W, Fawcett DW. A Textbook of Histology. Philadelphia: WB Saunders, 1975.)

• Actin filament bundles, hexagonally packed, are interposed between the sER cisternae and the plasma membranes.

A similar-appearing junctional complex in the Sertoli cell is also present at the site where the spermatids are attached. However, no tight junction is present, and the spermatid lacks flattened cisternae of sER and actin filament bundles (see Figs. 21.16 and 21.17). Other junc-

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