The pyramidal tract of the hedgehog (Erinaceus europaeus) and its relationship with the olfactory bulb.

The pyramidal tract of the hedgehog has been investigated. The motor cerebral cortex was first located electrophysiologically and subsequently ablated. Ablation of the motor cortex did not apparently cause motor deficits. The cerebral hemisphere of the operated side, brain stem and spinal cord were removed for histological examination. The Nauta-Gygax and the horseradish peroxidase methods were employed to study the course and origin of the above mentioned tract. The pyramidal tract runs ipsilaterally in the cerebral peduncle, and does not go beyond the first cervical segments of the spinal cord (C3-C4); moreover, their fibers do not cross at spinal level. The close relation between this anatomical pathway and the olfactory bulb of the same side is also reported.