EFFECTS OF SUBCUTANEOUS SALINE INJECTIONS ON GROWTH AND KERATINIZATION OF MOUSE TAIL EPIDERMIS

[摘要] The normal mouse tail epidermis develops a granular layer around the hair follicles and in the zone lateral to each scale. The tail scale regions do not form a granular layer. Epidermal keratinization is also different around the follicles to that in the scales. The perifollicular horny layer fluoresces red with Congo red and contains little phospholipid. The tail scales contain appreciable bound phospholipid and fiuoresce blue with congo red. The daily injection into the deep dermis of the tail of a small quantity of sterile isotonic saline without added preservative resulted after one month in a local alteration of epidermal growth and keratinization. Epidermal mitosis was increased, the epidermis was markedly thickened, and a prominent granular layer was formed in the tail scale region as well as around the follicles, The keratin fluorescence (and bound phospholipid distribution) was altered so that red and blue fluorescing keratins appeared in alternate layers in both the follicular and scale regions. The increased epidermal mitosis is probably explained by the pressure stimulus on the epidermal basal cells. Trauma to the epidermis through the injection of too much saline was avoided. The induction of a granular layer in the abnormal site of the tail scales and the keratinization change are not readily explained by the increase in epidermal mitotic rate. Other possible effects of the saline on the dermis besides pressure which might indirectly affect the epidermis are discussed. It is suggested that the keratin changes reported are partly due to the increased epidermal proliferation and partly to the induction of a new granular layer. The abnormal keratinization occurring in human skin after prolonged edema may have a similar cause to the keratin changes produced by experimental saline injections in mouse tails.