A double label retrograde tracing study of the olivocerebellar projection to the pyramis and uvula in the rat.

Microinjections of fluorescent tracers (Nuclear Yellow and Fast Blue) were used to study the organization of olivary cells in nucleus beta which give rise to climbing fibers to the medial zone of the uvula and the intermediate zone of the pyramis. It was determined that most cells in nucleus beta project to one or the other of these cortical sites. A third, smaller, population of cells were double labeled and, therefore, have climbing fiber axon collaterals which innervate these two cortical regions. There was no discernable segregation of these three populations of cells within nucleus beta.