Post-Operative Time Effects after Sciatic Nerve Crush on the Number of Alpha Motoneurons, Using a Sterological Counting Method (Disector)

There are extensive evidences that show axonal processes of the nervous system (peripheral and/or central) may be degenerated after nerve injuries. Wallerian degeneration and chromatolysis are the most conspicuous phenomena that occur in response to injuries. In this research, the effects of post-operative time following sciatic nerve crush on the number of spinal motoneurons were investigated. Twelve adult male Wistar rats, whose left sciatic nerves were highly compressed for 30 s, assigned to experimental groups 1 and 2 (n = 6). After 3 and 8 weeks post-operative (in groups 1 and 2 respectively) the lumbar segments of spinal cord were sampled, processed, sectioned serially and stained with toluidine blue (pH 4.65). By using stereological quantitative technique (physical disector), the number of alpha motoneurons in the right and the left ventral horns of spinal cord were counted and compared with each other. Statistical analyses showed a remarkable reduction in the number of alpha motoneurons in the left side (experimental or operated) when compared with the right side (control or unoperated) both in 3 and 8 weeks post-operative groups. This reduction may be due to the blockade of retrograde axonal transport.