The concept of transient radial glial cells, based originally on observations made on the human fetal brain stained with the classical Golgi silver impregnation method, has been evolving with the application of advanced methods of anatomy, molecular biology and genetics. In addition to providing scaffolding for migration and placement of neurons, these specialized cells can generate neuronal cell lineage that either immediately, or following multiple divisions, migrate along the elongated radial process of the mother cell. Comparative analysis of the data on emergence, function and morphogenetic transformation of radial glial cells in the mouse, macaque and human embryonic cerebral wall reveals both similarities as well as species-specific differences in the timing, sequence, biochemical composition and level of phenotypic differentiation that provide insight into cortical development and evolution, as well as into pathogenesis of genetic and acquired cortical abnormalities.