A Golgi analysis of unlayered polymicrogyria.

The cytoarchitectonics of the cerebral unlayered polymicrogyria located at the borders of a bilateral porencephalic defect is characterized by minute convolutions not exteriorized by sulci, in which blood vessels and increased numbers of fibrillary astrocytes are present in the fused molecular layers. The cellular organization, based on the analysis of Golgi sections, differs among gyral, intermediate, and sulcal regions and represents variable degree of cellular damage and structural organization of the cerebral mantle injured approximately in gestational month 5. Polymicrogyria may be produced by incomplete ischemia of radial territories vascularized by cortical blood vessels penetrating at right angles from the surface which is the result of the imbalance between the impaired cerebral blood flow of occluded large prerolandic arteries, responsible for the porencephalic defect, and the arterial meningeal anastomoses. Abnormal folding in polymicrogyria may be generated by lateral differences in the cortical thickness of adjoining areas, and by the imbalance in growth rates of laterally contiguous cortical regions.