Human Motor Cortex First Lamina and Gray Matter Special Astrocytes: Development and Cytoarchitecture

Abstract

During the development of the mammalian cerebral cortex, the gliogenesis of the different glial cell types parallel the evolution of its various compartments. Each basic glial cell type evolves at specific time, occupies a specific compartment, and develops specific morphological and functional features. The following glial cell types are recognized in the developing mammalian cerebral cortex: radial glia cells, white matter fibrous astrocytes and oligodendrocytes, subependymal polymorphous astrocytes, first lamina special astrocytes, and the gray matter protoplasmic astrocytes. The developmental history of each type is characteristic and occurs at specific time. The developmental histories and morphologic features of most glial cells types have been well documented (Rakic 1972, 1988; Marín-Padilla 1995). However, the late developmental gliogenesis of both the first lamina astrocytes and the gray matter protoplasmic astrocytes are less well documented. First lamina special astrocytes are needed for the late maintenance of the cerebral cortex expanding external glial limiting membrane (EGLM) and the protoplasmic astrocytes are necessary for the late gray matter neuronal and vascular maturations (Marín-Padilla 1995).