The effects of vitamin A on the epidermis of the fetal mouse in organ culture—an ultrastructural study

Skin pieces from 14-day fetal mice were cultivated for 1, 2, 3, 6, 7, and 10 days, then fixed in Zenker's fluid or glutaraldehyde for study by light and transmission electron microscopy. Epidermal differentiation in the standard culture medium was similar to that observed in vivo. When 6 μg/ml of retinol was added to the medium, discontinuities appeared in the basal lamina after 1 day. These gaps persisted after 2, 3, and 6 days, permitting numerous close contacts between basal epidermal cells and dermal cell processes. After 3 days in vitamin A medium, new “periderm-like” granules appeared in the stratum granulosum. Tonofilament bundles were less numerous than in normal medium, whereas Golgi stacks and vesicles were more numerous. It is suggested that basal lamina breakdown may permit the redirection of epidermal cell differentiation in the presence of vitamin A.