A gradient of adhesive specificity in developing avian retina.

Cell-cell adhesion was examined in the developing chick neural retina. A dorsoventral gradient of adhesive specificity in dissociated cells was detected which exhibits a complementarity such that the highest cell-cell affinities are exhibited between cells derived from the extremes of the gradient. If a nasotemporal gradient exists it must exhibit significantly lower cell-cell affinity. The relevance of these findings to pattern formation in the nervous system is discussed.