Glandular Metaplasia of Hair Follicles and Other Responses to Vitamin A Excess in Cultures of Rodent Skin

The study investigated the effects of excess vitamin A on hair follicle development in organotypic cultures of embryonic mouse skin. It was found that while pelage follicles from 15-day embryos initially differentiated normally, they regressed in vitamin-treated groups, unlike the control group where normal differentiation continued. Vibrissal follicles from the upper lip showed glandular metaplasia after 4 days of excess vitamin A exposure, transforming into gland-like structures, whereas control follicles developed normally. The study suggested that vitamin A induced metaplasia during a critical stage of follicle development, with some follicles recovering their ability to differentiate normally. The metaplastic glands resembled immature salivary glands, and an increase in sebum-like secretion was noted.