Correlation between differences in the structure of dendrite bundles and cytoarchitectonic patterns in the cerebral cortex of the rabbit.

The bundling patterns of apical dendrites are investigated in the neocortex of adult rabbits using 10-15 microns paraffin serial sections. In order to extend observations to 12 neocortical areas, four vertical planes of sectioning differing with regard to their angle with the frontal plane are chosen. In alternate sections, stained with either Klüver-PAS or a modified Gomori-method, the shape and structure of dendrite bundles are investigated in relation to the cytoarchitectonic pattern. In all 12 areas, bundling of apical dendrites is found both in lamina IV and II/III. Differences in bundle structure are found to be more pronounced amongst bundles in lamina IV than in lamina II/III. The principal difference between the bundling patterns in the precentral (motor) and occipital (visual) areas known from previous studies is confirmed, i.e. in the precentral areas short and stout bundles with a complex arrangement of apical dendrites are encountered, whereas in the occipital areas long and slender bundles with a simpler alignment of dendrites are found. Bundling patterns in the temporal cortex resemble the ones found in the occipital areas, whereas in the postcentral areas bundles are seen which show characteristics common to bundles of both the precentral and occipital areas.