Ventral root avulsions of the cat spinal cord at the brachial plexus level (cervical 7).

The ventral cervical 7th root was avulsed from the surface of the cat spinal cord, and studied using light microscopical stainings (Nissl, acetylcholinesterase and antibodies against neurofilament and glial fibrillary acidic protein) after different survival times. After two days the density of the neurofilament increased in the neurons in the ventral horn of the avulsed ventral root. Changes in the rough endoplasmatic reticulum (Nissl and acetylcholinesterase) started four days postoperatively, and were confirmed electron microscopically. The glial fibrillary acidic protein-positive structures surrounding the injured neurons in the avulsed ventral horn became more pronounced 30 days postoperatively. The number of neurons was definitely decreased 60 days after the avulsion. After the initial phase of the avulsion and before the distinct decrease in the number of neurons, the conditions for reimplantation of the avulsed ventral root and for the supposed regeneration can be expected to be more favourable for the neurons in the ventral horn.