Quantitative analysis of lamina III pyramidal neurons in the parietal cortex of newborns

The stage of neuronal development in the parietal (postcentral) cortex of human newborns was studied quantitatively in postmortem cases of different gestational (37th or 40th week) and postnatal age (2 hours or 3 weeks). In GOLGI-impregnated tissue obtained by autopsy, layer III pyramidal neurons were investigated. Comparatively, data were collected about dendrite parameters such as dendritic branching, length and spine density. The spine distribution (number and density) at the apical main dendrite, the apical tuft dendrites and in single basal dendritic fields as well, typically for the human layer III pyramidal neuron at the end of the gestational period, is described. Dendritic parameters from basal dendritic fields were compared in the three cases investigated (37th week with 2 hours or with 19 days of survival; 40th week of gestation with 2 days of survival). The large increase in spine number and density, especially in the second and higher orders of dendritic branching was obvious in the 19 days old infant brain. Special pathological aspects of the cases influencing the neuronal development are discussed. By means of a computerized method, quantitative data characterizing the human lamina III pyramidal neuron at the end of gestation are provided.