Some observations on the cerebellopontine projections in the cat--with a hypothesis to explain species differences.

The projection from the lateral and interposed nuclei of the cerebellum to the pons was investigated by means of autoradiography of anterogradely transported tritiated leucine. Dense termination, in part of axo-somatic nature, was observed in clusters within the central part of the nucleus reticularis tegmenti pontis. Termination in the pontine nuclei proper was found in small clusters directly ventral to the medial lemniscus and in trace-like amounts in the paramedian subnucleus. The results are discussed in relation to ponto-cerebellar circuits and comparative neuroanatomy.