Glandular metaplasia of hair follicles and other responses to vitamin A excess in cultures of rodent skin

The demonstration of mucous metaplasia in chicken embryonic epidermis exposed to an excess of vitamin A (Fell & Mellanby, 1953) stimulated many further investigations (reviewed by Fell, 1964; Fell & Rinaldini, 1965; Dingle & Lucy, 1965), leading to new insights into control of differentiation and function at the cellular level. The object of the present experiments was to study the effects of excess vitamin A on another keratin-producing system, the developing hair follicle, in organotypic cultures. Hairs and their follicles have received little attention from other investigators of vitamin A effects in vitro , although Fell & Mellanby (1953) referred to ‘evidence of an inhibitory effect on hair formation’ in some preliminary experiments with mouse embryonic skin, and New (1963) reported that ‘usually the development of hair follicles was suppressed’ in cultures of embryonic skin from the rat and mouse, both in the presence and absence of excess vitamin A.