AbstractThe behavior of epidermal cells was studied by employing two in vitro systems in which reepithelialization occurs: the single explant system and the fused system. Single explants (4–5 mm2) are prepared from the tailfins ofR. catesbeianatadpoles and cultured in Hank's balanced salt solution at 22°C. The fused system is prepared by placing single tailfin pieces on either side of a tailfin piece that was stripped of its epidermis. These tissues are placed onto a Millipore filter and cultured in Hank's at 22°C. In these experiments one can study the effect of the substrate, core vs a collagenous basement membrane, on the behavior of epidermal cells during reepithelialization.The results of these experiments demonstrate that there are differences in the behavior of epidermal cells in these two systems. In the fused system wound closure is associated with the occurrence of “contact inhibition,” the cessation of further cell migration, and the presence of an epidermal layer that exhibits a normal cytoarchitecture in the wound area. However, in the single explant system, wound closure occurs but an overaccumulation of epidermal cells in the wound area, “capping,”