Vimentin expression in spermatogenic and Sertoli cells is stage-related in rat seminiferous epithelium

Monoclonal and polyclonal antibodies were used in indirect immunofluorescence microscopy to localize vimentin intermediate filaments in the rat seminiferous epithelium. During stages XII-V of the epithelial cycle, the Sertoli cells showed a reaction in the perinuclear area and vimentin-positive extensions, projecting toward the developing spermatid bundles, were also seen. During stages VI-XI these extensions were small and narrow. Monoclonal antibody to vimentin gave a granular reaction in the peripheral region of the flagella of steps 16-19 spermatids. Western blotting indicated a specific reaction with a Mr 58,000 polypeptide in isolated seminiferous tubules and in epididymal spermatozoa. Our results suggest that vimentin filaments in Sertoli cells may be regulated cyclically in a stage-dependent manner. The granular reaction in the spermatid flagellum with the monoclonal antibody suggests that vimentin in germ cells is organized differently from that in somatic Sertoli cells.