Agents that cause enlargement of sebaceous glands in hairless mice. I. Topical substances.

We have developed a simple murine model to measure the effects on sebaceous glands of a variety of substances commonly found in topical formulations. Applications (0.2 ml) were made daily to the flanks of hairless albino female mice, for time periods varying from 4 to 9 days. Biopsies, fixed for light microscopy, were stained with H & E. Under x400 magnification, the sebocytes comprising each gland were counted, from which the mean sebocyte count per gland was calculated. Electron micrographs were prepared to evaluate sebum production. The test substances, which included anionic and cationic surfactants, solvents and emulsifiers, almost invariably led to a rapid increase in the sebocyte count, peaking at day 5. Irritating substances, such as croton oil and benzalkonium chloride, had the greatest hyperplasiogenic effect, at least doubling the sebocyte count. Electron micrographs showed large increases in rough endoplasmic reticulum and in sebum droplets. Thus, hyperplasia appears to be a stereotypic response to diverse substances, especially if these have irritancy potential.