Ventral horn motoneurons 10, 20 and 52 weeks after T-9 spinal cord transection.

To determine if transneuronal degeneration occurs in ventral horn motoneurons caudal to a spinal cord transection, we completely transected the spinal cord at T-9 in seven-week-old female rats. Ten, 20 or 52 weeks later, the motoneurons of the right sciatic nerve of transected and control rats were retrogradely labeled with Fluoro-Gold. There were no differences between control and transected rats in numbers or rostrocaudal distribution of labeled motoneurons at either 10, 20 or 52 weeks. At 20 weeks, there was no significant difference between control and transected rats in mean cross-sectional area of labeled neurons. We conclude that transneuronal degeneration did not occur.