Morphological Study of Spatial Distribution of Vestibulospinal Neurons in the Frog Rana ridibunda

In the thew frog Rana ridibunda, local microphoretic injections of horseradish peroxidase into various parts of spinal cord were used for study of trajectory of retrograde enzyme-labeled fiber systems and topography of labeled neurons in vestibulospinal nuclei, the source of vestibulospinal fibers. The vestibulospinal tracts were shown to be formed by neurons of lateral vestibular nucleus, although descending vestibular nucleus also is partially involved, while medial vestibular nucleus contributes to even lesser degree. Besides, study of spatial distribution of C- and L-vestibulospinal neurons in the frog did not confirm the presence of the definite somatotopy that is characteristic of vestibular nuclei in mammals.