Brainstem afferents to the thalamus in a lizard, Varanus exanthematicus

HRP was injected into various thalamic nuclei in order to investigate the brainstem projections to the thalamus in the lizard Varanus exanthematicus. Nucleus dorsomedialis receives afferents from the septal area, nucleus entopeduncularis anterior, nucleus periventricularis hypothalami, area triangularis, nucleus raphes superior, nucleus reticularis inferior, and locus coeruleus. Nucleus dorsolateralis receives afferents from septal area, nucleus dorsomedialis, nucleus entopeduncularis anterior, nucleus periventricularis hypothalami, and the torus semicircularis. Nucleus rotundus receives an input from the tectum mesencephali, the pretectal area, and from the mesencephalic reticular formation. Nucleus intermedius dorsalis receives afferents from the dorsal column nuclei and nucleus periventricularis hypothalami. Nucleus ventrolateralis receives afferents from the dorsal column nuclei, the trigeminal complex, locus coeruleus, and the reticular formation. Nucleus ventromedialis also receives afferents from the trigeminal complex and the reticular formation. Afferents to the habenula have been demonstrated from the septal area, nucleus entopeduncularis anterior, triangular area, nucleus periventricularis hypothalami, nucleus interpeduncularis, nucleus raphes superior, locus coeruleus, nucleus isthmi, nucleus dorsalis motorius nervi vagi, and the mesencephalic tegmentum. The laminar part of the torus semicicularis projects to nucleus medialis.