Identification of pontocerebellar axon collateral synaptic boutons in the rat cerebellar nuclei.

Injections of the orthogradely transported tracer PHA-L into the basilar pontine nuclei or reticulotegmental nucleus of hooded rats produced labeling of pontocerebellar axons that distributed to the cerebellar cortex and nuclei. EM examination of the lateral and interposed cerebellar nuclei revealed that labeled pontocerebellar axon terminals formed synaptic boutons in the cerebellar nuclei that were morphologically different from the characteristic mossy fiber terminals observed in the cerebellar cortex.