ANTIBODIES AGAINST THE T61 ANTIGEN INHIBIT NEURONAL MIGRATION IN THE CHICK OPTIC TECTUM

Cell migration in the central nervous system depends, in part, on rece ptors and extracellular matrix molecules that likewise support axonal outgrowth, We have investigated the influence of T61, a monoclonal ant ibody that has been shown to inhibit growth cone motility in vitro, on neuronal migration in the developing optic tectum, Intraventricular i njections of antibody-producing hybridoma cells or ascites fluid were used to determine the action of this antibody in an in vivo environmen t, To document alterations in tectal layer formation, a combination of cell-nuclei staining and axonal immunolabeling methods was employed, In the presence of T61 antibody, cells normally destined for superfici al layers accumulated in the ventricular zone instead, leading to a re duction of the cell-dense layer in the tectal plate, Experiments with 5-bromo-2'-deoxyuridine labeling followed by antibody staining confirm ed that the nonmigrating cells remaining in the ventricular zone were postmitotic and had differentiated, The structure of radial glial cell s, as judged by staining with a glia-specific antibody and the fluores cent tracer -dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlo rate (DiI), remained intact in these embryos. Our findings suggest tha t the T61 epitope is invoiced in a mechanism underlying axonal extensi on and neuronal migration, possibly by influencing the motility of the leading process.