The Journal of comparative neurology
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Retrograde transport studies revealed that the nuclei pallidus, obscurus, and magnus raphae as well as the adjacent reticular formation innervate the spinal cord in the opposum. HRP-lesion experiments showed that a relatively large number of neurons within the nucleus obscurus raphae and closely adjacent areas of the nucleus reticularis gigantocellularis project through the ventrolateral white matter and that many cells within the nucleus magnus raphae, the nucleus reticularis gigantocellularis pars ventralis, and the nucleus reticularis pontis pars ventralis contribute axons to the dorsal half of the lateral funiculi. Neurons within the rostral pole of the nucleus magnus raphae and the adjacent nucleus reticularis pontis pars ventralis may project exclusively through the latter route. ⋯ The immunohistofluorescence method revealed evidence for indolaminergic axons in each of the spinal areas labeled by injections of 3H-leucine into the raphe and adjacent reticular formation. They were particularly abundant within the intermediolateral cell column and within laminae IX and X. These data indicate that raphe spinal systems are chemically and connectionally heterogeneous.
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Connections of two telencephalic vocal control nuclei, the hyperstriatum ventrale, pars caudale (HVc), and robust nucleus of the archistriatum (RA), were investigated in adult canaries. Methods used were transport of horseradish peroxidase and 3H-adenosine and silver staining of degenerating axons. Three nuclei project to HVc: medial nucleus magnocellularis of the anterior neostriatum (MAN), nucleus interfacialis (NIf) of midneostriatum, and nucleus uvaeformis (Uva) of the diecephalon. ⋯ All these projections are ipsilateral. No gross male/female differences were apparent in the projections to and from HVc. Uptake of HRP by cell somata in HVc following localized injections of this substance into RA or HVc suggests that HVc is composed of rostrocaudally organized clusters of cells, with little lateral communication between them.