EN
Pontine nuclei (PN) are large center transferring cortical afferents to the cerebellum. The study addresses to distribution of PN neurons in the pontocerebellar link. Two different neuroplasmatic and nuclear fl uorescent tracers were injected in separate experiments into: (1) paramedian lobule (PML) and pyramis, and (2) pyramis and uvula. Following both combination of injections, retrogradely labeled neurons were found bilaterally in all PN apart from the ventral nucleus. These neurons, parent for the pontocerebellar projection, clustered in two groups. First larger group occupied the dorsolateral nucleus and the dorsolateral region of lateral and peduncular nuclei. Second smaller group involved the dorsal region of paramedian nucleus and the dorsomedial region of peduncular nucleus. Projection to the uvula arises from nearly entire rostrocaudal extent of PN, and that to the pyramis and PML originates from medial and caudal extent of PN. In spite of substantial overlap of projection area in PN, no neurons were found to project by way of axonal collaterals. The strongest PN projections arise from the dorsolateral nucleus and these from the paramedian, lateral and peduncular nuclei are about two, three and fi ve times weaker, respectively. PML and the uvula receive the most numerous projections (mean 4 744 and 4 283 neurons) whereas projection to the pyramis (mean 1 172 neurons) is apparently smaller. The differences in the projection seem to be cause of different function of these lobules.