COMPARATIVE HISTOCHEMICAL OBSERVATIONS ON WOUND HEALING IN ADULT RATS AND CULTURED ADULT HUMAN EPITHELIUM .2. RIBONUCLEIC ACID AND THYMONUCLEIC ACID

[摘要] During wound healing, epidermis undergoes first a phase of cellular migration followed by one of growth. In rats, the latter phase is characterized by an increased concentration of cytoplasmic ribonucleic acid. This is restricted to those cells where mitosis occurs, namely in the basal and lower stratum spinosum layers. A similar response is found in cultured human epithelium also being limited to those layers where proliferation occurs. During culture, explants frequently reveal areas of separation at the dermo-epidermal junction. Epithelium overlying these areas is morphologically abnormal with degeneration in the lower layers and preservation of a basal cell appearance in the more superficial layers. A close similarity exists between epithelium migrating over denuded burn surfaces and the outwandering cells found in culture. In both cases the initial migration is followed by intense proliferation just within the borders either of the surrounding normal skin (in burns) or of the explant (in culture). Mitosis occurs to a lesser extent in the outwandering epithelium during culture, but a large percentage of these are abnormal. Thymonucleic acid concentration of the nuclei either in burns or culture does not appear to vary appreciably. The ribonucleic and thymonucleic acid metabolism of epithelial cells during in vivo wound healing and in in vitro cultures appears identical.