Distribution of concanavalin A receptor sites on specific populations of embryonic cells.

The early 32- to 64-cell stage of the sea urchin embryo consists of three cell types, easily distinguishable by size: micromeres, mesomeres, and macromeres. Only the micromeres are migratory. Treatment of dissociated sea urchin embryo cells with fluorescein-labeled concanavalin A (Con A) revealed a Con A-induced highly clustered or capped distribution of receptor sites on the micromeres. Concanavalin A did not induce significant clustering or capping of receptor sites on the mesomeres or macromeres. The results indicate that Con A receptor sites are more mobile on specific population of malignant-like migratory embryonic cells.