The olivocerebellar projection to the uvula in the mouse.

The organization of the olivocerebellar projection in the mouse was studied with the use of microinjections of horseradish peroxidase (HRP) or HRP conjugated to wheat germ agglutinin (WGA-HRP). Injections were made in medial, intermediate, and lateral sites along the width of the uvula. The purpose of this investigation was to determine the subnuclear origin of olivary afferents to different mediolateral regions of the uvula. Injections made in or adjacent to the midline of the uvula resulted in the retrograde labeling of cells, bilaterally in the caudal portion of the medial accessory olive (MAO). These labeled cells were located primarily in subnucleus C and nucleus beta of the MAO. Injections into the intermediate part of the uvula resulted in the labeling of cells in the caudal MAO (primarily nucleus beta), the dorsomedial cell column (dmcc), and a few cells in the ventral lamella of the principal olive (vPO). Laterally placed injections produced labeling of cells in dmcc and the vPO. These results are discussed in reference to the parasagittal organization of olivary afferents to the cerebellar cortex in the mouse (Beyerl et al., '82) and the organization of afferents to the involved regions of the inferior olivary (IO) complex. It is suggested that these parasagittal zones in the uvula may play different roles in the control of eye movements.