PERTURBATION OF THE DEVELOPING XENOPUS RETINOTECTAL PROJECTION FOLLOWING INJECTIONS OF ANTIBODIES AGAINST BETA(1) INTEGRIN RECEPTORS AND N-CADHERIN

We have examined the function of beta(1) integrin receptors and N-cadh erin in the development of the Xenopus retinotectal projection. In viv o perturbation experiments were performed by injecting antibodies dire cted against beta(1) integrin receptors and N-cadherin into the embryo nic optic pathway. The antibodies were present during the initial deve lopment of the retinal projection, when the axons of the ganglion cell s are migrating through the optic tract and terminating within the opt ic tectum. When injected individually, the antibodies were insufficien t to cause obvious pathfinding errors. However, when injected together , the antibodies caused specific abnormalities in the development of t he retinotectal projection. Pathfinding errors most commonly observed included ectopically projecting axons within the optic tract region, m eandering and splaying of axons in the optic tectum, and the induction of prominent ipsilateral projections. IgGs and Fab' fragments of the antibodies produced pathfinding errors; these defects were not observe d in animals injected with control antibodies. These in vivo results s how that pi integrin receptors and N-cadherin have important roles dur ing the development of the visual projection and provide evidence that a balance between cell-cell and cell-matrix adhesion may be critical for the normal development of the vertebrate visual system. (C) 1996 A cademic Press, Inc.