Distribution of radial glia in the developing telencephalon of chicks

Radial glia are known to have a sparse and uneven distribution in the telencephalon of adult birds. The present study utilizes antibodies against vimentin to reveal a more extensive, and more clearly radial, set of radial glia in the chicken telencephalon during the first half of embryogenesis. This initially extensive radial glial fiber system becomes distorted and reduced between 10 and 14 days of incubation. This reduction coincides with the cytoarchitectural differentiation of the telencephalon into its major adult subdivisions. Because developing neurons tend to migrate along radial glial fibers in both birds and mammals, a topological projection of these major subdivisions onto the embryonic ventricular zone along the radial glial fibers suggests hypotheses about lineage relationships that can be tested by subsequent experimental methods. This analysis suggests that the major components of the avian dorsal ventricular ridge, i.e., the ventral hyperstriatum, the neostriatum with its various subdivisions, part of the archistriatum, and probably also the piriform cortex, all derive from overlapping portions of the lateral pallial ventricular zone. Staining with antibodies against neurofilament suggests that this developmental parcellation of the lateral pallial complex is associated with the development of neuronal fiber systems.