We have pursued studies of the role of extracellular materials in the control of epithelial morphogenesis, and in the mechanism and cellular consequences of intercellular adhesion. In these latter studies, emphasis was on avoidance of freshly trypsinized cells and on the relationship between adhesion and ionic coupling. We intend to continue these studies in an attempt to identify the molecules involved and to determine how they act in controlling epithelial shape changes, and in forming stable intercellular bonds, as well as in the cellular response to bond formation. Focus will be on: (1) using epithelia isolated retaining the basal lamina and epithelia from which the lamina has been removed to analyze glycosaminoglycan metabolism and the structural organization of the laminar components, including collagen; (2) assessing the role of the lamina in the regulation of actin filament organization by analysis of the organizational state of the actin, and, in the control of cellular proliferation by utilizing a factor which promoted DNA synthesis; (3) modifying cell surfaces to correlate the loss or alteration of surface components with the effect of the modification on intercellular adhesion; (4) using pre-formed embryonic cell aggregates and layers to establish the relationship of intercellular adhesion to ionic coupling and to changes in cell proliferation.