The organization of microtubules and filamentous actin in cytospin preparations of Sertoli cells from w/wwei mutant mice devoid of germ cells.

The microtubule (MT) cytoskeleton and the distribution of filamentous actin (F-actin) were examined in the w/wwei mutant of the house mouse (Mus musculus), which is characterized by the absence of germ cells. Cytospin preparations of carefully minced testis tubules were stained with one of three different monoclonal antitubulin antibodies or with phalloidin conjugated with a fluorescent dye. The antibodies were directed to beta-tubulin, acetylated alpha-tubulin, and tyrosinated alpha-tubulin. The antibody to beta-tubulin revealed prominent MT bundles oriented parallel to the long axes of the Sertoli cells. Acetylated alpha-tubulin was present only in a small subset of the MTs close to the nuclei, and tyrosinated alpha-tubulin was virtually missing in polymerized MTs. This pattern does not correspond to that reported for Sertoli cells in wild mammals. Thus, the absence of germ cells apparently affects the microtubular cytoskeleton. Our study showed that this also applies to F-actin. Bundles of F-actin were found throughout about two thirds of the Sertoli cells cytoplasm lateral to the nucleus in w/wwei mice. In contrast, F-actin was reported to form sheets throughout the cytoplasm in wild-type mice. F-actin is part of the so-called ectoplasmic specializations--elements that are involved in the contact between the spermatids and Sertoli cells. Thus, the absence of germ cells from testes appears to have far-reaching effects on the cytoskeleton of the Sertoli cells.