Golgi study of the nucleus of the transpeduncular tract in the rabbit.

Abstract

AbstractThe nucleus of the transpeduncular tract was studied in Golgi, reduced silver, and Nissl series of the brain stems of newborn and adult albino rabbits. The nucleus contains cells which differ with respect to their dendritic orientation, dendritic pattern, and size. The terms intranuclear and extranuclear are further used to designate those cells respectively whose axons are restricted to the nucleus or are projected outside the nucleus. The intranuclear cells usually lie ventrally, and their axons distribute dorsally, within the nucleus; and on this basis, the nucleus is divisible into ventral and dorsal divisions. The axons of some of the extranuclear cells studied project and terminate within the substantia nigra, midbrain reticular formation, or red nucleus; whereas the axons of others pass into the transpeduncular tract or medial lemniscus.This study reveals that individual axons of the transpeduncular tract terminate in ventral or dorsal nuclear divisions and suggests that the transpeduncular tract input comprises the largest projection to the nucleus. Axons of cells of the substantia nigra, as well as axons passing from the midbrain reticular formation and probably the anterior accessory optic tract, are shown to terminate primarily within the dorsal division of the nucleus. Axons from the cerebral peduncle are found to end mainly within the ventral division of the nucleus. The findings are discussed in relation to existing biological data.