Immunocytochemical demonstration of cytoskeletal proteins in seminiferous tubules of adult rams and bulls.

The immunohistochemical localization of actin, vimentin and tubulin in adult ovine and bovine seminiferous tubules was studied at both the light and electron microscopical levels, using an improved methodical protocol. alpha-smooth muscle actin and structural F-actin were found to be present in myoid peritubular cells. Structural F-actin also occurs in Sertoli cells at three localizations; 1) As part of the Sertoli-Sertoli-junctions in a stage-dependent manner; 2) where Sertoli cells are in contact with spermatocytes; 3) in ectoplasmic specializations lining the recesses that support elongating spermatid heads. Vimentin is localized in peritubular myoid and fibroblastic cells and in Sertoli cells. In the latter, vimentin is concentrated in a perinuclear position. alpha-tubulin is observed in the cytoplasm of spermatogonia, in axonema and manchette of spermatids and in Sertoli cells with their abundant microtubules. Since the alpha-tubulin reaction decorates even the narrowest lateral and apical cell processes, it is an excellent marker to study changes in Sertoli cell shape and size during the seminiferous epithelial cycle in rams and bulls.