Morphology of single neurones in the cerebello-rubrospinal system.

Axonal branching patterns of physiologically identified cerebellar nucleus neurones and rubrospinal neurones were investigated in the cat with intra-axonal injection of horseradish peroxidase and 3-dimensional reconstruction on serial sections. Axons of dentate and interpositus neurones projected to the VL nucleus of the thalamus and on their way, several axon collaterals were given off from the stem axons to the red nucleus. Axon terminals of interpositus neurones terminated as a sagittal sheet of arborizations in the red nucleus. Their terminal boutons made apparent contact with cell bodies and proximal dendrites of rubrospinal neurones. In rubrospinal axons, multiple axon collaterals were identified at different segments of the cervical spinal cord.