Changes in retrogradely labelled neurones in the red nucleus and cortex after depletion of motoneurones by axotomy in neonatal rats.

Following nerve injury to the sciatic nerve in neonatal rats many motoneurones die, so that the target of the rubrospinal and corticospinal cord is altered. Retrograde labelling of neurones terminating in this region shows that, in the red nucleus as well as cerebral cortex, there is a significant reduction in labelled neurones on the side contralateral to the nerve injury. Thus neurones in the brain that give rise to descending fibres are influenced by the altered environment in the spinal cord following axotomy at birth.