Dentate nucleus of Ateles ater. Cytomorphometric analysis.

A morphometric analysis of the dentate nucleus of A. ater was performed. Numerical cell densities, cell size, and gray cell coefficients were determined. The selection of this primate was predicated upon phylogenetic and cytoarchitectural criteria. This griseum is cytomorphologically identical to the human dentatum. Quantification was made with both phase contrast and bright-field optics. The gray cell coefficients were determined by Haug's point-counting method. The dentate nucleus is characterized by the presence of large and small neurons and the typical three glial elements. The ratio between the numerical cell densities of the large and small cells was 1:1. The oligodendrocytes had the highest numerical cell density, followed by the astrocytes, and the Hortega cells. The total glia index was computed to be 13.14. In the corpus medullare, the oligodendrocytes presented the highest numerical cell density; the numerical cell densities of the Hortega cells and the astrocytes were not significantly different from each other. Linear measurements of the glial nuclei revealed that the astrocytes were the largest of the glial elements, showing no difference in size between gray and white matter. The size of the oligodendrocytes in the dentate nucleus corresponded to their size in the white matter. In the corpus medullare, the Hortega cell nuclei are shorter in length than those found in the gray substance. The gray cell coefficients were transformed into volume percentages. Only 9% of the dentate nucleus is composed of nerve cell perikarya and glial cell nuclei; the glial cell nuclei represent only 2% of the total white matter. The morphometric differences existing between the cellular elements in both gray and white substance is correlated with the functional roles ascribed to the neuroglia in relation to capillary and neuronal density. The glial 'satellites' are predominately oligodendrocytes.