Immunocytochemical localization of synaptophysin on the smooth-surfaced tubular membranes present in nerve terminal and preterminal areas in the rat cerebellar cortex.

The distribution of synaptophysin, a major protein of the synaptic vesicle membrane, was immunocytochemically examined in the rat cerebellar cortex. A monoclonal antibody against synaptophysin recognized the epitope to be present in the presynaptic membranous structures including synaptic vesicles, presynaptic membrane, coated vesicles, and vacuoles of endocytotic origin. In the nerve terminal as well as preterminal areas, the antibody labeled the smooth-surfaced tubular membranes which were located in the relatively interior parts of these areas and consistent in size and appearance with the short tubules comprising the thinner parts of the axonal reticulum. However, the antibody did not stain the short tubular membranes, though similar in appearance to the above, which existed right below the axolemma in the preterminal and nerve terminal areas. The results are discussed with special reference to the precursor membrane compartments of synaptic vesicles.