| Abstract: | In cultures of dissociated chick sympathetic ganglia, retrograde (somatopetal) movement of concanavalin A receptors in the axolemma can be observed directly. Such movement was visualized by using concanavalin A coated red blood cells (ConA-RBCs) as membrane markers. Forty-eight percent of all ConA-RBCs which bound to sympathetic nerve fibers moved somatopetally at rates ranging from 11-84 μ/hr with a mean and standard error of 49 ± 6 μ/hr (n = 18). On nongrowing nerve fibers, the ConA- RBCs within 60 μ of the cell body showed retrograde movement, while on elongating neurites only those markers within 30 μ showed such movement. The rate of retrograde ConA-RBC movement appeared to increase with distance from the cell soma. The binding of ConA-RBCs to sympathetic neurites was specific for concanavalin A receptors since pretreatment with either concanavalin A or α-methylglucopyranoside prevented this binding. Untreated polystyrene beads (1.1 μ) which bound nonspecifically to the neurite membrane also showed retrograde movement. These beads moved somatopetally at rates similar to those of the ConA-RBCs but did so regardless of their initial distance from the soma. These data suggest that retrograde movement of surface elements might be a general property of cultured sympathetic nerve fibers. |
