Laminin as a substrate for retinal axons in vitro.

Fetal mouse retinal ganglion cell axons have been shown to ramify within co-cultured basement membrane secreting tumor explants and upon isolated basement membranes. Here we report that laminin, a glycoprotein found in basement membranes and adhesion sites of a variety of cell types, acted as a substrate for retinal explant attachment and axonal outgrowth. When axons were given a direct choice, laminin was preferred over collagen. Under suitable conditions (air-dried upon underlying collagen gels), laminin was more effective than fibronectin for promoting axon emergence from retinal explants. These findings have implications for the study of molecular mechanisms underlying CNS axonal outgrowth.