Expression and localization of desmosomal proteins in developing human skin at 8, 11, and 21 weeks of EGA and at newborn age (NB). Note the gradual increase in the density of desmosomes. At 8 weeks EGA, the epidermis is composed of basal and peridermal cell layers (a, e, i). Antibodies to desmoplakin (a), desmocollin (e), and desmoglein (i) label cell membranes of basal and peridermal cells. Note also immunolabeling in the dermal-epidermal junction. At 11 weeks EGA, the intermediate cell layer has developed in the epidermis (b, f, j). An intense signal for desmoplakin (b), pan-desmocollin (f), and pan-desmoglein (j) is apparent in the peridermal cells. Intermediate cells also show desmosomal antigens, while lateral membranes of basal cells are almost devoid of these desmosomal proteins. At 21 weeks EGA, the peridermal cell layer has been shed and the epidermis is composed of the four definitive layers of epidermis (c, g, k). Desmoplakin (c), desmocollin (g), and desmoglein (k) antibodies label all the cell layers, the basal cells being only weakly labelled (arrowheads point to the dermal-epidermal junction; bars (a, e, i) 10 m, (b, c, d, f, g, h, j, k, i) 20 m).
