The Cerebral Hemispheres

The development of the cerebral hemispheres requires an orderly succession of events beginning with proliferation and differentiation of the periventricular germinal cells into neuroblasts and glial precursors. Then, the neuroblasts and the glial precursors migrate to the cortical plate, laying down the ground for the walls and gray structures of the future hemispheres. Once the neuro-blasts, guided by the radiation glia, reach the cortical plate in an inside-to-outside sequence, they grow, mature into neurons, organize into laminae, and eventually establish synaptic connections. Excess neurons are destined to die by the process of apoptosis (programmed cell death). Interference with proliferation, migration, and laminar organization of the neurons results in a broad spectrum of malformations involving (a) the cerebral mantle—that is, the hemispheric wall, and (b) the convolutions and cortical cytoarchitecture.

0 0

Post a comment