Heterogeneous distribution of bullous pemphigoid antigen during hair development in the mouse.

The appearance and localization of one of the basement membrane constituents, the bullous pemphigoid antigen, were studied during the development of hair follicles in the mouse. The analysis was performed, with the indirect immunofluorescent method, on frozen sections of dorsal skin, between 14 days of gestation and 10 days post partum. Specific labelling was restricted to the epidermal-dermal junction (EDJ). The earliest positive reaction was seen in 15-day embryos as a continuous underlining of the EDJ. At later stages throughout embryonic development and up to 10 days post partum, in hair rudiments labelling of the EDJ was interrupted. In particular, the EDJ along the underside of hair placodes and nodules, the lower half of follicles at the bulb and hair cone stage, as well as around the dermal papilla was not or very faintly labelled. By contrast, in the upper portion of follicles and interplumar skin, the EDJ was brightly labelled. It is concluded that bullous pemphigoid antigen is absent or scarce in zones of morphogenetic activity, where epidermal-dermal interactions are supposedly exerted, whereas it is present in zones of histological stability.