A developmentally regulated antigen associated with neural cell and process migration

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Abstract
The distribution of an epitope recognized by the monoclonal antibody JONES has been studied immunohistochemically in the developing nervous system of the rat. In the present report, we survey selected regions of the fetal, postnatal, and adult rat nervous system to test the hypothesis that JONES binding is invariably associated with neural cell migration and axon growth in the developing rat. A series of selected developmental stages extending from embryonic day (E) 9 to adult were used in this investigation. The distribution of JONES binding was examined using indirect immunofluorescence, as well as the immunogold procedure. Particular attention was paid to regions where the positions and timing of cell and axon migrations have been well described for the rat. JONES immunoreactivity first appears at E 11-12, when it is localized to the lamina terminalis, the telencephalic-diencephalic junction, the midbrain, and the rhombic lip regions of the cytologically undifferentiated neural tube. In all the regions studied, during embryonic and early postnatal life, the labeling is very intense in the ventricular zone and shows a radial array in the adjacent intermediate and marginal zones. The expression of JONES epitope correlates particularly with times of cell migration in the retina, superior colliculus, cerebellum, and telencephalon and in regions undergoing neurite extension, such as the developing optic tract, the white matter of the cerebellum, the dorsal roots, the trigeminal system, and olfactory nerve. JONES binding becomes progressively restricted in the postnatal period. In the adult brain, immunoreactivity is presented only in the retina and cerebellum. In the retina, JONES labeling is present in the outer plexiform layer and optic fiber layer. The labeling in the optic fiber layer extends to the optic nerve head and stops abruptly outside the orbit. In the cerebellum, JONES shows a radially oriented pattern throughout the molecular layer and delineates the cell bodies in the Purkinje cell layer. The only non-neural regions that show JONES immunoreactivity are the adrenal medulla and the kidney glomeruli. We conclude that the antigens recognized by the JONES monoclonal antibody are associated with the migration of subsets of cells and axons within the developing rat nervous system and, consequently, may play a role in conveying selectivity to these processes.