Annual Meeting of the Society for Neuroscience edition:33 location:New Orleans, U.S.A. date:November 8-12, 2003
In contrast to the overwhelming information about the mammalian dorsal lateral geniculate nucleus (LGN), there is an astonishing lack of information concerning the neuronal organization, including neuronal morphology and neurochemical phenotype, of the ventral LGN (vLGN) in cat and the pregeniculate nucleus (PrGC) in monkey. This immunocytochemical study revealed distinguished neurochemical reactivity for neurofilament protein and seven neuronal markers to characterize the GABAergic cell population, i.e. GABA, calbindin, calretinin, parvalbumin, neuropeptide Y, enkephalin and somatostatin within cat vLGN and monkey PrGC. A characteristic neurofilament protein expression profile was apparent allowing the delineation of these subcortical nuclei into two subzones in both species. Calretinin, neuropeptide Y and enkephalin are efficient anatomical markers allowing for the parcellation of monkey PrGC in two subdivisions. In cat, GABA, parvalbumin and enkephalin immunoreactivity clearly demarcated the medial part from the lateral part of the vLGN. Based on characteristic neurochemical marker expression profiles within the vLGN and PrGC and on the position of both subcortical structures in the lateral geniculate nucleus complex, these findings suggest a well-defined part of the cat vLGN and monkey PrGC as homologue of the rodent intergeniculate leaflet. Three-dimensional reconstructions of this complete subcortical structure together with the dorsal LGN elucidate the true anatomical constellation of cat vLGN and monkey PrGC.