Expression and in vitro Function of p,-lntegrin Laminin Receptors in the Developing Avian Ciliary Ganglion

In chick development, ciliary ganglion (CG) neurons go through a period of axon extension from approximately em-bryonic day (E)4 to E8, followed by a period of synapto-genesis and neuronal cell death. By examining the immu-nohistochemical localization of laminin, in conjunction with Dil labeling of the ciliary nerve projection, we have deter-mined that the pathway taken by these neurons is rich in laminin expression. Therefore, laminins are good candi-date molecules for mediating outgrowth of these neurons in viva. In vitro, the ability of CG neurons to extend neurites on laminin-1 (EHS laminin, culplyl) is maximal up to E8, then declines dramatically. CG neuron outgrowth on lami-nin-1 requires the activity of &-class integrins. We have used subunit-specific antibodies to determine which of the five &-containing heterodimers known to be laminin recep