Autoradiographic study of glycoprotein synthesis during embryonic epidermogenesis of the mouse in vitro

Forelimb buds of mouse embryos (day 11 + 3 h of development) were cultured for 6 days. During this period, the epidermis developed from a two-layered stage (basal and periderm cell layer) to a multilayered squamous epithelium wih stratum granulosum and stratum corneum. To investigate the glycoprotein synthesis during epidermogenesis in vitro, the limb buds were labeled for 30 min or 4 h with 3H-fucose at successive stages of development. Until the development of the stratum intermedium, no different labeling of the individual layers of the epidermis and the periderm was observed. Shortly before the beginning of the stratum granulosum, a strong labeling of the outer region of the intermediate layer, where the shape of the cells had changed from cuboid to flat, was visible. When the stratum granulosum developed, even in this layer and in the upper stratum spinosum, strong glycoprotein synthesis was observed, indicated by strong labeling with 3H-fucose. In the developing stratum corneum, no labeling of this layer was detectable 30 min or 4 h after 3H-fucose application. Labeling of peridermal cells was weak in the early stages of development and ceased in the period of stratum granulosum formation, indicating a stop of glycoprotein synthesis in this embryonal cell layer before its disappearance.