Article

Anuran dorsal column nucleus: Organization, immunohistochemical characterization, and fiber connections in Rana perezi and Xenopus laevis

Department of Cell Biology, Universidad Complutense de Madrid, Spain.
The Journal of Comparative Neurology (Impact Factor: 3.51). 01/1996; 363(2):197-220. DOI: 10.1002/cne.903630204
Source: PubMed

ABSTRACT As part of a research program on the evolution of somatosensory systems in vertebrates, the dorsal column nucleus (DCN) was studied with (immuno)histochemical and tract-tracing techniques in anurans (the large green frog, Rana perezi, and the clawed toad, Xenopus laevis). The anuran DCN contains some nicotinamide adenine dinucleotide phosphate diaphorase-positive neurons, very little calbindin D-28k, and a distinct parvalbumin-positive cell population. The anuran DCN is innervated by primary and non-primary spinal afferents, by primary afferents from cranial nerves V, VII, IX, and X, by serotonin-immunoreactive fibers, and by peptidergic fibers. Non-primary DCN afferents from the spinal cord appear to arise throughout the spinal cord, but particularly from the ipsilateral dorsal gray. The present study focused on the efferent connections of the DCN, in particular the targets of the medial lemniscus. The medial lemniscus could be traced throughout the brainstem and into the diencephalon. Along its course, the medial lemniscus gives off collaterals to various parts of the reticular formation, to the octavolateral area, and to the granular layer of the cerebellum. At mesencephalic levels, the medial lemniscus innervates the lateral part of the torus semicircularis as well as various tegmental nuclei. A striking difference between the two species studied is that while in R. perezi medial lemniscal fibers do not reach the tectum mesencephali, in X. laevis, intermediate and deep tectal layers are innervated. Beyond the midbrain, both dorsal and ventral thalamic areas are innervated by the medial lemniscus. The present study shows that the anuran "lemniscal pathway" is basically similar to that of amniotes.

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    • "As in birds and mammals, a projection to the torus semicircularis mediated by the medial lemniscus and originating from the DCN or one of its funicular nuclear homologs has been described in a teleost (Finger, 2000) and in amphibians (Muñoz et al., 1995). In fish and amphibians, auditory (octaval), mechanosensory and electrosensory inputs to the torus have traditionally been described as terminating separately (Bell, 1981; McCormick, 1982; 1989; De Wolf et al., 1983; Haugede-Carre, 1983; Echteler, 1984; Finger and Tong, 1984; Boord and Northcutt, 1988), but in birds, reptiles and lamprey there seems to be some overlap of auditory and somatosensory inputs to the torus (Belekhova et al., 1985; Künzle, 1986 Wild, 1995; present study; Gonzáles et al., 1999). "
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    • "In N.IX–X, cell perikarya and neurites were immunolabeled with the calbindin antibody (Fig. 1 A). Calbindin expression elsewhere in the rhombencephalon was limited to the Purkinje cells of the cerebellum, cells of the dorsal tegmental area of the medulla, and sparse cells in the reticular formation and central gray as well as the dorsal rhombencephalic calbindin-expressing nuclei previously described by Muñoz et al. (1995) "
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    The Journal of Comparative Neurology 03/1996; 367(1):54-69. DOI:10.1002/(SICI)1096-9861(19960325)367:1<54::AID-CNE5>3.0.CO;2-I · 3.51 Impact Factor
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