IMMUNOHISTOCHEMICAL STUDIES OF GLIOGENESIS IN THE RAT CENTRAL NERVOUS SYSTEM (GLIOSIS, OLIGODENDROCYTE, ASTROCYTE, GANGLIOSIDE)

Abstract

Oligodendrocyte and astrocyte lineages were traced in rat forebrain sections using single and double label immuno-peroxidase and indirect immunofluorescent techniques. Oligodendrocytes are derived from small, G(,D3)+ subventricular zone (SVZ) cells, beginning at embryonic day 16 (E16), while glial fibrillary acidic protein (GFAP) astrocytes are derived from vimentin+ radial glia that are established by E15. Four pieces of evidence support an embryonic separation of the oligodendrocyte and astrocyte lineages: (1) G(,D3)+ cells acquired oligodendrocyte specific markers, carbonic anhydrase (CA) and iron and with time became galactocerebroside+ (GC); (2) vimentin+ and GFAP+ cells were not also G(,D3)+; (3) ultrastructural localization of anti-G(,D3) was confined to cells with features of developing oligodendrocytes; and (4) the shapes of G(,D3)+, CA+, GC+ or iron+ cells did not resemble those of the vimentin+ or GFAP+ cells.;The temporal and spatial development of oligodendrocytes in several regions of the rat brain was also studied. The large, G(,D3)+/CA+/iron+ generated by the SVZ migrated into white and gray matter. Those entering white matter underwent gradual transformations in shape while those entering gray matter rapidly became process-bearing. Cells in subcortical white matter with early transitional shapes had a ('3)H-thymidine labeling index greater than 9% after a 6 hr pulse, while cells with morphologies representing more advanced states of differentiation had an index less than 1.5%.;Oligodendrocytes in the internal capsule, posterior subcortical white matter, and cerebellum originated, respectively, from the SVZs at the interventricular foramen, adjacent to the side of the lateral ventricle, and the roof of the fourth ventricle. Oligodendrocytes in the hippocampus originated from a SVZ that surrounded the periphery of the hippocampus and that extended into the hippocampal fissure.;The cellular localization of G(,D3) in gliotic tissue was also explored using the anti-G(,D3) and anti-GFAP antibodies together in double staining immunofluorescence experiments. The cytoplasmic processes and cell bodies of astrocytes displayed positive membrane staining with the anti-G(,D3) antibody.