Commissural projections of the superior vestibular nucleus in the rat

Wheatgerm agglutinin horseradish peroxidase (WGA-HRP) injections confined to the superior vesicular nucleus (SVN) of six Fischer 344 rats labeled commissural vestibular neurons (CVN) in central and ventral portions of contralateral SVN and Group Y nucleus (Grp Y). When the injection included medial vestibular nucleus (MVN) and Grp Y, labeling was similar with additional labeling in contralateral ventrolateral MVN. A dried pledget of WGA-HRP placed in a midline IV ventricle lesion (N = 4), bilaterally labeled SVN and Grp Y (MVN could not be assessed) CVN. While Grp Y CVN are significantly smaller (138.8 +/- 64.7 microns2) than the CVN in the SVN (177.9 +/- 73.9 microns2) or MVN (196.2 +/- 61.9 microns2), cellular eccentricity (shape) is similar in all three nuclei (0.80, 0.77, SVN, MVN, Grp Y).