Retinoic Acid and Mouse Skin Morphogenesis. II. Role of Epidermal Competence in Hair Glandular Metaplasia

The study investigated the effects of retinoic acid (RA) on mouse skin morphogenesis, particularly focusing on the development of glomerular glands instead of hair vibrissa follicles in the upper-lip skin. The research tested whether the up-regulation of the β retinoic acid nuclear receptor (RARβ) was involved in altering dermal-epidermal interactions during the development of skin appendages. The study used RA-treated and untreated skin explants from nasal, upper-lip, and dorsal mouse embryonic tissues, analyzing them through in situ hybridization and morphological phenotype identification. The findings indicated that RARβ expression was specific to facial mesenchyme and was not directly related to hair glandular metaplasia. Instead, this metaplasia depended on a glandular bias in the upper-lip epidermis and a reduction in hair follicle-inducing properties of the dermis, which was affected by RA treatment in both upper-lip and dorsal regions.