The influence of laminin on the initial differentiation of cultured neural tube neurons.

Portions of the metencephalic neural tube containing the trigeminal (V) motor nucleus from 40-hr chick embryos were excised and held freely floating in culture medium for 36-40 hr, so that neuronal generation within motor V could be completed, but precluding neuronal differentiation. The explants were then dissociated and plated either on 1) glass coverslips that had been coated with the extracellular matrix (ECM) glycoprotein, laminin, and subsequently irradiated to produce a grid pattern; or 2) coverslips, one-half of which had been coated with laminin, and the other one-half with collagen, another component of the ECM. The purpose of these studies was to assess possible laminin influences on neuronal adhesion and nerve fiber expression and extension during these periods of initial neuronal differentiation. The early neural tube neurons selectively adhered to the established laminin grid pattern; neuronal survival, elaboration of neurites, and extent of neurites were significantly enhanced on the laminin side of the laminin/collagen preparations. These latter effects were specifically blocked by the application of anti-laminin. In demonstrating these influences during stages of initial neuronal differentiation, the results support the hypothesis that laminin may play a role in normal neurogenesis, presumably by providing an adhesive surface for outgrowing growth cones.