The JONES monoclonal antibody has been immunocytochemically associated with regions of the developing rat brain where cell and axon migrations are occurring (Mendez-Otero et al., 1986, 1988). In the present study the antigens recognized by the JONES antibody were analyzed in a variety of brain regions and at developmental ages selected to correspond to the preceding immunocytochemical observations. In accordance with earlier results from retina, JONES binding could not be detected in SDS gels from developing brain. Binding of the antibody was, however, prominent in chloroform/methanol extracts of the same tissues, and it was completely removed from tissue sections by brief chloroform/methanol form/methanol treatment. Enzymatic analyses of chloroform/methanol extracts indicated that the JONES epitope was sensitive to neuraminidase but insensitive to proteases. Overlay assays on developed high-performance thin-layer chromatographic plates (HPTLC) indicate that in all regions the JONES epitope resides on 2 or 3 ganglioside bands, depending on the age examined. These bands migrate between ganglioside standards GD 1a and GM2 on HPTLC plates and have been designated GJ1, GJ2, and GJ3, with the higher number designating the more rapidly migrating species. Occasionally, additional bands migrating in the range of polysialogangliosides were observed. The pattern of expression of GJ species was studied in forebrain, retina, and cerebellar tissue taken from embryonic day 18 (E18), postnatal day 0 (P0), P7, P14, and adult animals. Both region-specific differences in the relative prominence of each band and stage-specific differences in the total amount of the JONES gangliosides were detected. The stage- specific differences in the amount of JONES antigens are well correlated with the developmental periods of maximal cell migration in each region. While the JONES gangliosides are most prominent in forebrain before birth, in they are most prominent during the first 2 postnatal weeks. In cerebellum, JONES antigen expression is more pronounced during the 2 periods of cell migration in this tissue. In retina, the more rapidly migrating GJ3 band was the most prominent band at all stages examined, and this same band is retained in the adult. In cerebellum and forebrain GJ3 is also the most pronounced band during development. However, in contrast to the retina, the more slowly migrating GJ1 band is retained in adult forebrain and cerebellum. A variety of non-brain tissues have also been examined for the presence of the JONES antigens.

We used the activity of nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) to detect the presence of nitric oxide synthase (NOS) in the developing rat superior colliculus. Our results showed that NOS is present in cells and neuropil in the developing and adult rat superior colliculus. The first NOS-positive cells were detected at postnatal day 7 and were weakly stained. During the following days the number of stained cells increased markedly, reaching a peak by postnatal day 15, coinciding with the time of eye opening in the rat. By the end of the third postnatal week, both the number and intensity of stained cells showed an adult-like pattern. We conclude that NOS expression lags behind the initial period of reorganization of the retinotectal projection. However, NOS activity could be involved in the subsequent synaptic remodeling and plasticity of the retinocollicular projection.

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 E11-12, 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 present 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.

Glial markers, namely, vimentin, glial fibrillary acidic protein (GFAP), and glycogen, as well as accumulation of axon-borne horseradish peroxidase (HRP), were used to visualize radial glial cells in the developing opossum superior colliculus (SC) and to follow changes in young astrocytes of the superficial layers. Vimentin, GFAP, and glycogen are relatively abundant in elements of the median ventricular formation (MVF), which persists at least as late as weaning time, i.e., postconception day 103, postnatal day 90 (PND90). Radial profiles and end-feet in the remaining collicular sectors (main radial system, MRS) are also vimentin-positive but show little or no glycogen or anti-GFAP staining. The numeric density of MRS profiles is very high at the final stages of neuronal migration (PND12) but falls to vestigial numbers by PND 56-60. Antivimentin staining and filling of MRS profiles by axon-borne HRP disappear in parallel. Before total regression of MRS profiles, young astrocytes of the superficial gray layer exhibit a transiently high GFAP expression that is not found in those of the subjacent layers. The results suggest that 1) radial glia at or near the collicular midline are well equipped for a mechanical supportive role, and their abundant glycogen accumulation may reflect their eventual transformation in cells with high glycolytic metabolism, including tanycytes; 2) in most collicular sectors, some radial glia cells persist for long periods after cessation of neuronal migration and may interact with afferent fibers coursing through the superficial neuropil; 3) radially oriented astrocytes of the superficial gray layer exhibit a transiently high GFAP expression that is temporally correlated with late transformations of the retinocollicular projections.