Dry condition affects desquamation of stratum corneum in vivo

We examined whether a dry condition actually induces scaly skin in vivo. Ha irless mice were kept in a high humidity condition or a low humidity condit ion and skin changes were examined. Scales appeared on the backs of mice ke pt for 3 days under the dry condition. The weight of stratum corneum (SC) w as increased at this point, and these alterations were not accompanied with hyperproliferation of the nucleated cell layer of the epidermis. A decreas e of desmosomal degradation was observed, though, desquamation-related enzy me activity was not altered. The regulation mechanism of desquamation is no t yet clear, however, in vitro experiments suggest that the water content i n SC is an important factor. The water content of SC was decreased in the d ry condition. These results indicate that a dry environment perturbs desmos ome degradation in intact SC by decreasing the water content of SC, and the consequent impairment of desquamation in normal skin in vivo may lead to t he induction of a scaly skin surface. (C) 1998 Elsevier Science Ireland Ltd . All rights reserved.