Precerebellar Cell Groups in the Hindbrain of the Mouse Defined by Retrograde Tracing and Correlated with Cumulative Wnt1-Cre Genetic Labeling

Abstract

The precerebellar nuclei are hindbrain and spinal cord centers that send fibers to the cerebellum. The neurons of the major hindbrain precerebellar nuclei are derived from the rhombic lip. Wnt1, a developmentally important gene involved in intercellular signaling, is expressed in the developing rhombic lip. We sought to investigate the relationship between the cell clusters expressing Wnt1 and the precerebellar nuclei in the hindbrain. We therefore defined the hindbrain precerebellar nuclei by retrograde tracing, following cerebellar injections of HRP, and compared these results with the cell clusters expressing Wnt1 in newborn mice. We found that 39 distinct hindbrain nuclei project to the cerebellum. Of these nuclei, all but three (namely the oral pontine reticular nucleus, the caudal pontine reticular nucleus, and the subcoeruleus nucleus) contain neurons expressing Wnt1. This shows a high degree of overlap between the precerebellar nuclei and the nuclei that express Wnt1. However, it should be noted that neurons expressing Wnt1 are also found in the superior olivary complex, which is a basal plate derivative lacking cerebellar projections.

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“…Wnt1 is a developmentally important gene involved in intercellular signaling that is expressed by CGNs in newborn mice [20]. …”

The Arcuate Nucleus of the C57BL/6J Mouse Hindbrain Is a Displaced Part of the Inferior Olive

“…Watson and Paxinos [2010] noted the presence of a similarly positioned nucleus in a calbindin-stained section in their chemoarchitectonic atlas of the mouse brain, and the presence of the nucleus was noted in a study of mouse precerebellar nuclei [Fu et al, 2011]. However, we have found no published account of the characteristics of this nucleus in mice.…”

“…The exclusively contralateral projection character of the arcuate nucleus is the same as that of the inferior olive. In this respect, the inferior olive and the arcuate nucleus differ from the precerebellar nuclei that give rise to mossy fibers because these nuclei project either bilaterally or ipsilaterally to the cerebellum [Fu et al, 2011]. Moreover, the arcuate nucleus was found to express several biomarkers that were also expressed in the inferior olive, and which were not expressed in the mossy precerebellar nuclei (lateral reticular nucleus, pontine nuclei, external cuneate nucleus and reticulotegmental nucleus of the pons).…”

Axonal Patterns and Targets of dA1 Interneurons in the Chick Hindbrain

“…Genetic strategies in mice extended the classical chick studies and revealed that dA1/Atoh1 ϩ neurons along the cRL assemble the ventral/dorsal CN and PCN (Wang et al, 2005;Okada et al, 2007;Fu et al, 2009Fu et al, , 2011Rose et al, 2009b). Application of intersectional/subtractive fate-map approaches further identified the contribution of rhombomere-specific interneurons to these nuclei (Farago et al, 2006;Maricich et al, 2009).…”