On the concanavalin A positive layer on the skeletal muscle fibre.

The localization and distribution of mannosyl and glucosyl residues on the extrajunctional sarcolemma of skeletal muscle fibres of frog, rat and new-born rat was studied by means of concanavalin A labelled with FITC and ferritin-concanavalin A conjugate. A strong fluorescent layer surrounding the muscle fibres was found out. Ultrastructurally concanavalin A binding sites were established on the outer surface of muscle cell membrane, on the basal lamina, on the space between them, as well as on the reticular lamina, which ensheeted the muscle fibre. The width of the concanavalin A positive layer was 0.3 to 0.7 micron. On the basis of intensity of the fluorescence, some differences in the content of mannosyl and glycosyl residues during ontogeny as well between both species was admitted.