Distribution of corpus callosum and anterior commissure in cat and raccoon

Abstract

The distribution of the forebrain commissures was studied using the Nauta‐Gygax silver technique. Following total forebrain commissure transection in the cat the striate cortex or visual area I was remarkably free of degenerating fibers, while peristriate or visual area II showed dense degeneration. Somatic sensory arm and distal hindlimb areas appeared degeneration free while proximal leg and face areas revealed heavy degeneration. The somatic motor area of the anterior sigmoid gyrus contained dense numbers of degenerating fibers. The auditory areas of ectosylvian gyrus showed moderate degeneration over their entire surface except the most ventrally situated cortical areas which were degenerated free. Fibers from the corpus callosum also terminated in the dorsolatearal portions of the head of the caudate nucleus. The anterior limb of anterior commissure distributed mainly to the inner granular layer of the olfactory bulb. In addition, it disseminated considerable numbers of fibers in the anterior olfactory nucleus. The accessory olfactory bulb was degeneration free. The distribution of the forebrain commissures in the raccoon was very similar to the cat. The outstanding feature of the commissural pattern in the raccoon was the total absence of degenerating fibers in the lobular complex relating to the digits of the forepaw.