MORPHOGENETIC DETERMINATION OF DERMOEPIDERMAL INTERFACE DURING TAIL REGENERATION IN RANA-CATESBEIANA

During regeneration of the amputated tadpole tail, reconstruction of the epithelial basal lamina and basement lamella occurs only after the other major morphogenetic processes are well established. At 4 days after tail transection of the bullfrog tadpole, EM of the internal surface of the basal cell layer of the blastemal epithelium reveals it to be relatively free of extracellular matrix. By 11 days a basal lamina of distinct regularity forms and the 1st rodlets and fibers signaling the replacement of the collagenous basement lamella are identified. At 15 days the basal cells of the epithelium start to exhibit specialization of their internal cell surfaces: hemidesmosomes and associated tonofilaments appear, and the adepidermal globular layer is formed. Orthogonal packing of collagen begins by 19 days after transection, the number of layers exceeding 22 in the latter stages of regeneration.