An autoradiographic study of midbrain-diencephalic projections to the inferior olivary nucleus in the opossum (Didelphis virginiana).
Techniques of intra-axonal transport were utlizied to elucidate the organization of diencephalic and midbrain projections to the inferior olivary nucleus of the Virginia opossum. Retrograde transport of horseradish peroxidase injected into the olive suggests that terminals within it arise from the subparafascicular nucleus of the caudal thalamus, the nucleus of Darkschewitsch, the fields of Forel, the interstitial nucleus of Cajal, the periaqueductal grey, the caudal pretectal nucleus, the tegmentum dorsomedial to the red nucleus, the red nucleus (minimal), the nucleus linearis, as well as the dorsolateral midbrain tegmentum and tectum (Henkel et al., '75). Tritiated leucine injections were made into each of the above-mentioned cell groups so that the olivary terminals of their axons could be demonstrated autoradiographically. In general, the projection systems show three basic patterns of organization. Ventromedial areas of the midbrain, including the ventral periaqueductal grey, the interstitial nucleus of Cajal, part of the red nucleus and the tegmentum dorso-medial to it, provide a substantial and topographically organized projection to the principal nucleus of the olive, as well as minor inputs to the accessory nuclei. Secondly, neurons within the subparafascicular nucleus, the nucleus of Darkschewitsch and the fields of Forel project most heavily to parts of the medial accessory nucleus, although they also provide input to the other major subdivisions of the olive. Third, axons from the dorsolateral tegmentum and tectum completely avoid the principal nucleus, while supplying small regions of the accessory nuclei.
D000818:Animals; D001345:Autoradiography; D001931:Brain Mapping; D004027:Diencephalon / Q000033:anatomy & histology*; D008636:Mesencephalon / Q000033:anatomy & histology*; D009434:Neural Pathways / Q000033:anatomy & histology; D009847:Olivary Nucleus / Q000033:anatomy & histology*; D009893:Opossums / Q000033:anatomy & histology*; D012012:Red Nucleus / Q000033:anatomy & histology; D013477:Superior Colliculi / Q000033:anatomy & histology; D013681:Tegmentum Mesencephali / Q000033:anatomy & histology; D013787:Thalamic Nuclei / Q000033:anatomy & histology