RATE OF REGENERATION OF PARTLY HISTOLYZED ANURAN TAIL SKIN

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Abstract
Uniform-sized, tail-skin grafts were secured from extreme anterior and posterior regions and from 2 intermediate areas and transplanted, autoplastically, to the back (Rana pipiens larvae). Artificial metamorphosis was induced and the engrafted integument removed at certain stages of histolysis and transplanted, horneoplastically, to the back or tail of normal larvae. Anterior tissue invariably regenerated with greater rapidity than posterior; intermediate tissue, at proportionate rates. Control homeoplastic transplantations of skin from: 4 regions of the tail, when grafted to the tail or back of normal larvae, clearly indicated that histolysis does not occur in larval tail-skin following transplantation to normal individuals. Histologically, the process of degeneration followed a definite, orderly sequence. Dissociation of various layers began prior to the appearance of lymphocytes in the histolyzing area. Lymphocytes probably functioned chiefly as phagocytes. The regenerative process was first evidenced, histologically, in the epidermal layers of the graft. The stratum compactum was the last layer of integument to regenerate completely. It is concluded that an anterior-posterior gradient in regenerative rate is true for tail integument following partial histolysis. Apparently, differences in regenerative rate of integument at different levels of the tail are inherent qualities. Possible physiological factors associated with such differences, however, are still undetermined.