[Neurohistological findings in the parietal cortex of children with chromosome aberrations].

In Golgi-Cox impregnated parietal cortex (regio postcentralis) of two children (20 months of age or 6 years of age) with Down's syndrome the pyramidal neurons of lamina III and V were investigated qualitatively and quantitatively. Fives types of pyramidal neurons were classified and compared statistically. As parameters for characterizing pyramidal neurons served dendritic lengths for all dendritic orders, within single dendritic fields, in apical and basal parts of the dendritic tree, and of the whole neuron. Normal values obtained in brains of the same age were not available, therefore, we compared our results with those published by other authors. To study the developmental stage of the pyramidal neurons in both our cases, we compared analogue pyramid types in both brains. The pyramidal neurons showed different qualitative abnormalities in their dendritic tree configuration. The comparison of quantitative parameters suggests the pyramidal cells of the older child show more degenerative changes, concerning especially lamina III pyramids but in lamina V pyramids as well. These changes might be structural correlates of the mental retardation: the 6 year old child was strongly retarded in clinical symptoms, too. The results are discussed and critically evaluated in view of the clinical signs of Morbus Down. Finally we should await the investigations of more cases for demonstrating the normal as well as the abnormal development of the human cerebral cortex.