The research aims at an understanding of the organization of basement membranes and the function of individual macromolecules or of assemblies for cellular function. It is proposed to study the self-assembly of and the interactions between type IV collagen, laminin, entactin and heparansulfate proteoglycans in vitro by physical and electronmicroscopical methods. Information provided by these in vitro assembly studies will be correlated with images obtained by direct imaging of a variety of basement membranes from several tissue sources - amnionic membranes, lens capsule, Descemet's membrane and Reichert's membrane. Imaging of tissues will be done by metal shadow casting methods using electron beam evaporation or Penning sputtering of carbon/platinum or with other metals under various conditions. In order to interpret such images, information provided by in vitro assembly will be important. In addition, we propose to analyze polymers of basement membrane molecules synthesized, deposited and assembled by cells in culture by direct imaging techniques or by using antibody conjugates for identification of specific molecules. It is anticipated, that the information provided by these studies will allow to describe a model for the organization of the rather complex macromolecules within the basal lamina. It will also allow to determine basic mechanisms for the changes observed in the basal lamina in disease states such as diabetes mellitus. It furthermore will allow to address the question of mechanisms by which cells residing on the basal lamina can maintain their differentiated state or which lead to abnormal growth.