Circumferential cells of the developing Rana catesbeiana lumbar spinal cord

Abstract

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.

Spinal cord neuron classes in embryos of the smooth newtTriturus vulgaris: a horseradish peroxidase and immunocytochemical study

“…Large cells with ventral commissural axons and dorsal processes have been reported in Rana catesbiana embryos (Campbell et al 1987), but the dorsal processes extend only as far as the midline, and do not reach the contralateral tract as Giant dorsolateral commissural interneuron processes do. Neurons with dorsal commissural processes are reported in the spinal cords of adult frogs and teleosts (Johnston 1908), but they do not appear to resemble the Giant dorsolateral commissural interneurons of urodele embryos in other respects.…”