The efferent connections of the cerebellar nuclei in the pangolin.

Abstract

AbstractThe connections of the cerebellar nuclei were traced in a primitive and specialized eutherian mammal, the pangolin, by placing varied unilateral lesions in the basal cerebellar nuclei and staining the ensuing fiber degeneration with the selective staining techniques of Marchi and Nauta. The results showed a cerebellifugal system that is basically similar to the pattern described for other mammals. The brachium conjunctivum arises primarily from the interpositus and dentate nuclei and follows the typical mammalian course and termination in the red nucleus and thalamus. In addition, a rather extensive termination in the dorsal mesencephalic tegmentum is present. A variation was observed in the descending limb of the brachium conjunctivum which divides into two tracts, medial and lateral. The fastigial projections are directed mainly to caudal rather than rostral areas with extensive terminations in vestibular and reticular areas.The present study establishes further the constancy of the general organization of cerebellar efferents in mammals and the primitive position of the cerebellifugal system in phylogeny. An assumption is made that the efferent connections of the cerebellum are present in one form in all therian mammals.