Genetic Expression and Morphogenesis of the Skin in Vertebrates

The study explored the effects of retinoic acid on morphogenesis and positional values in vertebrate skin, highlighting its ability to induce additional structures similar to homeotic mutations. Experiments showed that retinoic acid could cause feather formation on chick embryo scales and transform mouse vibrissa hair buds into glands. The research focused on the expression of retinoic acid nuclear receptors (RARs) during normal hair follicle development and retinoic acid-induced changes, noting that RAR alpha and gamma were active in normal conditions, while RAR beta was expressed following retinoic acid treatment, leading to gland formation. The study emphasized the importance of dermal-epidermal interactions in skin differentiation, though the communication mechanisms between these tissues remained largely unknown.