Relatively little is known about the organization of neural input to pelvic viscera in amphibia. In this study, sacral spinal efferent neurons were labeled in Xenopus laevis frogs by application of horseradish peroxidase (HRP) to the tenth spinal nerve, to pelvic musculature, or to the pelvic nerve. DiI was applied to the pelvic nerve with similar results. Labeled spinal neurons were located in the intermediate gray or in the ventral horn. Neurons in the tenth dorsal root ganglion, but not in the spinal cord, were labeled after application of HRP or DiI to the pudendal nerve. The labeled neurons in the spinal cord intermediate gray were in a position comparable to that of the mammalian sacral parasympathetic nucleus (SPN). Two apparent subdivisions included 1) a medial cluster of cells with mediolaterally oriented dendrites and 2) a lateral group with dorsoventrally oriented dendrites. An intermediate group, not clearly classed with the other two, was also identifiable. In some cases, labeled tenth nerve primary afferents were seen in contact with efferent neurons of the intermediate gray. Labeled neurons in the ventral horn medial to the lateral motor column were small, with dendrites oriented mediolaterally, in a position comparable to that of the mammalian Onuf's nucleus. The peripheral targets of DiI-labeled pelvic nerve axons were the compressor cloaca muscle, cloaca, and bladder. DiI-labeled pudendal nerve axons distributed peripherally to cloacal lip and medial thigh integument. These data suggest that the pudendal nerve in amphibians is purely sensory and that both somatic and autonomic motor axons traverse the pelvic nerve.
Neural elements in the lumbar enlargement of the developing Rana catesbeiana spinal cord were labelled by placing chips of dessicated horseradish peroxidase (HRP) into various lesions of the spinal cord. Of the elements labelled in the lumbar enlargement, a population of cells circumjacent to the gray matter was seen to be distinct from all others on the basis of their morphology, position and their putative embryonic origin. One cell type not previously described was a large circumferential cell (LCC) with primary processes completely circumscribing the gray matter. The ventral process crosses the midline and ascends or descends in the ventral funiculus. The dorsal primary process was observed to extend to the midline and turn ipsilaterally in a rostro-caudal direction in the dorsal funiculus. LCC's were present at early stages of larval development (stage III, Taylor and Kollros 1946) but could not be labelled in juvenile frogs. LCC's were only observed in the lumbar enlargement and could only be labelled through HRP applications at that level. They receive abundant synaptic input from the ipsilateral lateral funiculus. Possible roles for the LCC in the early function and development of the ranid lumbar spinal cord are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.