Aberrant dendritic development in the human agyric cortex: a quantitative and qualitative Golgi study of two cases.

A quantitative and qualitative Golgi comparison of the visual cortex from two agyric brains and of two age-matched controls is reported. In the camera lucida drawings, most pyramidal cells were oriented vertically to the pial surface in the external cellular layer, frequently with their apical dendrites directed toward the deep layers (inverted pyramidal neurons). The deep cellular layer contained pyramidal and polymorphic neurons normally found in the second to fourth cortical layers. In quantitative analysis of the agyric cortex of a ten-month-old patient, relative immaturity of basal dendritic arborization was apparent together with a bipolar configuration of dendritic development of the pyramidal neurons. The 3-year-old patient had a significant delay in apical dendritic arborization (shorter branch length, decreased number of dendritic intersections) compared with his age-matched normal control. The pathogenesis of the abnormal dendritic development in agyria is discussed.