Distribution of the neurons of origin of the great cerebral commissures in the cat.

Large injections of horseradish peroxidase throughout major portions of the right cerebral hemispheres of four cats revealed extensive distributions of the neurons of origin of the corpus callosum, the anterior commissure and the hippocampal commissures in the uninjected left hemispheres. The distributions of labelled neurons were mapped by semiautomatic computer microscope. The radial and tangential neuron distributions presented here are of a higher density and greater extent than those in previously published studies based on injections of transportable label to more circumscribed areas of the cerebral cortex of the cat. Generally, commissural neurons in the cat were distributed in a bilaminar fashion with supragranular cells more numerous than infragranular cells.