Effects of steroid hormones on developing mouse skin in vitro.

Pieces of skin from 13-5- to 15-day-old foetal mice were grown in organ culture in a biological medium with or without the addition of hormonal steroidsmcortisol (7-5 mug/ml) caused thinning of the non-cornified epidermis and flattening of the stratum granulosum after 3 days. By 6 days the epidermis was thinner and hair follicles were regressing, and these changes continued up to 12 days. Administration of corticosterone (5 mug/ml) also produced thinning of the epidermis and regression of the follicles after 6 days. Good differentiation of epidermis and hair follicles was obtained when testosterone (100 mug/ml) was added to the medium. The non-cornified epidermal layers were similar to those of control cultures at 3 days but less than half as thick at 6 days. Hair follicles differentiated as rapidly in medium containing testosterone as in normal medium, but, unlike in the latter medium, also developed sebaceous gland anlagen at 6 days. Some explants in testosterone medium showed signs of sebaceous cell differentiation at 9 days.