Defective terminal differentiation and hypoplasia of the epidermis in mice lacking the Fgf10 gene

Here, we characterized the skin and hair phenotype of mice lacking the fibroblast growth factor 10 gene (Fgf10), a newly identified member of the fibroblast growth factor family. Histological examination of Fgf10(-/-) newborn mouse skin revealed abnormalities in epidermal morphogenesis. The number of proliferating cells in the basal layer was decreased, the granular layer was hypoplastic and lacked distinctive keratohyaline granules and tonofibrils. The expression of loricrin, a marker of epidermal differentiation, was dramatically reduced. Despite the presence of Fgf10 transcripts in normal hair follicles, abnormalities of hair development were not observed in Fgf10(-/-) skin. These data suggest that Fgf10 is required for embryonic epidermal morphogenesis but is not essential for hair follicle development.