Matrix‐cytoskeletal interactions in the developing eye

AbstractThe embryonic avian corneal epithelium in vitro responds to extracellular matrix (ECM) molecules in either soluble or polymerized form by flattening its basal surface, organizing the basal cortical actin cytoskeleton, and stepping up its production of corneal stroma twofold. Embryonic corncal epithelia, like hepatocytes and mammary gland cells, seem to contain heparan sulfate proieoglycan (HSPG) in their plasmalemma, which may interact with actin on the one hand or underlying collagen on the other. Work on the corneal epithelium suggests that, in addition to HSPG, specific glycoprotein receptors for laminin and collagen exist in the basal plasmalemma and play, the critical role in actually organizing the basal epithelial cytoskeleton. As yet. uncharacterized proteins may link such receptors to actin. We suggest that ECM‐dependent organization of the cytoskeleton is responsible for ECM enhancement of corneal epithelial differentiation. Cell shape and exogenous ECM also affect mesenchymal cell differentiation. In the case of the conical fibroblast migrating in collagen gels, an actin cortex present around the elongate cell seems to interact with myosin in the cytosol to bring