Retinoic acid induction of featherlike structures from reticulate scales

Retinoic acid‐induced transformation of reticulate scales to feather‐like structures (Dhouailly and Hardy, '78) provides a useful model to study biochemical differentiation in avian skin. In this study, immunofluorescent analysis of reticulate scale‐feathers (RSFs) indicates that they contain β keratin in feather barbs and, thus, are true feathers, biochemically. Epidermal cells that would otherwise produce only α keratin in reticulate scales are induced to reorganize and differentiate into barb ridge cells that accumulate feather β keratins. The mechanism for these dramatic morphological and biosynthetic responses to retinoic acid is unknown.