The presence and localization of different cytoskeletal proteins in Salmo gairdneri spermatozoa have been analyzed by several methods, including immunofluorescence, immunoelectron microscopy and immunoblotting. Antibodies against actin, desmin, vimentin and tubulin were used to study the cytoskeletal organization of sperm heads and tails. Actin was found, although scarce, in heads and in tails; desmin immunoreactivity was confined to the sperm head; vimentin was negative. Tubulin, besides its obvious presence in the sperm tail, was also localized in the sperm head
