Heterotypic fibrils and stabilizing collagens in corneal development

Abstract

Our studies on the embryonic development of the chick cornea have recently yielded information suggesting possible roles for different types and classes of collagens. The chick cornea develops through a series of precisely controlled temporal and spatial events involving cell differentiation, migration and extracellular matrix production and assembly. Each event involves, and is possibly dictated by, dramatic changes in the major molecular components of the extracellular matrix. Corneal morphogenesis begins with the formation of the primary corneal stroma, a dense subepithelial matrix consisting of orthogonally arranged, horizontal layers of collagen fibrils. Each layer is one fibril thick. This stroma then rapidly swells and immediately thereafter is invaded by pericorneal mesenchymal cells. These cells differentiate into stromal keratocytes and synthesize the secondary, mature stroma, a structure in which each orthogonal layer is many collagen fibrils thick.