[Comparison of the histochemical bases of epidermis differentiation in vertebrates].

It was been shown that in the line of forms of amphibia, reptiles, mammals, including man, the histochemical differentiation of the epidermis is related with changes in protective and transitory zones. For instance, in amphibia the accomodation to the terranian medium is accompanied by establishment of the vertical histochemical gradient in the epidermis which is manifested by accumulation of a protein rich in cationic and sulfhydril groups in the protective zone. The epidermis of reptiles is characterized by presence of high concentrations of a protein rich in cystine in the protective zone. The transient zone is formed on the border of the protective and germinative zones. The epidermis of mammals retains in general features the histochemical type of differentiation of the protective zone which had appeared in reptiles. However, the transient zone of the mammalian epidermis has a high concentration of proteins rich in histidine and arginin. The histochemical differentiation of the human epidermis is related with the distribution of the hairy integument.