Vitamin a and βcarotene concentrations at different depths of the epidermis: A preliminary study in the cow snout

Abstract

Vitamin A (retinol) is an anti-keratinizing agent essential for normal epithelial differentiation. In order to examine the epidermal distribution of vitamin A and provitamin A (βcarotene), we took advantage of the extraordinarily thick snout epidermis of the cow which can be cut horizontally into at least 6 layers, representing keratinocytes at different stages of maturation. Extracts of saponified samples were analyzed for retinol and βcarotene by reversed phase high-performance liquid chromatography. The highest retinol concentration (0.8 μg/g protein; n=3) was recorded closest to the dermis; progressively decreasing amounts of retinol were found in the upper parts of epidermis. Maximum values of βcarotene (1.0 μg/g; n=7) were found in the lower parts of epidermis; substantially lower levels were seen at the dermal transition zone and in the upper parts of epidermis. The results suggest that the endogenous concentration of vitamin A in snout epidermis is inversely related to the degree of cellular differentiation. © 1987 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.