[Developmental aspects of regeneration of the spinal cord (observations on chick embryos)]

The reaction of the embryonic spinal cord to mechanical transversal myelotomy has some general features: 1. It is above all a glial reaction and repair by a glial scar which is the more subtle, the younger the damaged embryonic tissue. 2. The younger the spinal cord, the more powerfully it responds by proliferative reactions. 3. We never observed restoration of the original spinal architecture. The older the embryo, the more marked the defects of the grey and white matter. 4. During transversal myelotomy in older embryos after damage of already develop spinal pathways irreversible disconnection of the spinal cord from higher compartments of the CNS occurs and this is manifested by a marked reduction of the spontaneous activity of the spinal generator of embryonic motorics with all sequelae for its further morphological and functional development.