Immuno-electron microscopical localisation of alpha-actinin and actin in microvilli of prostatic epithelial cells.

The localisation of alpha-actinin and actin was investigated immunocytochemically in microvilli of rat ventral prostatic epithelial cells fixed by a solution containing 1.25% glutaraldehyde and 1% paraformaldehyde. Both proteins were localised in the microvilli by immunoperoxidase labelling of semithin or ultrathin sections. Almost the whole microvillous core region was labelled by antibodies for actin. Most of the label for alpha-actinin was confined to the region close to the plasma membrane along the length of the microvilli. In addition, positive staining was found at the microvillous tip and weak staining at a small area in the core. These results suggest a role of alpha-actinin in the stabilisation of actin filaments in these regions.