Retrograde labeling to assess axon regeneration.

<p>Sciatic nerves were cut and repaired by end-to-end anastomosis. The mean (<u>+</u>SEM) number of motoneurons whose axons had regenerated at least four mm into the distal stump and were labeled by retrograde tracer applied via nerve soak three weeks after transection and repair is shown in panel A. The mean (<u>+</u>SEM) number of motoneurons whose axons had regenerated successfully and had re-innervated the lateral and medial gastrocnemius muscles after tracer injection into muscles four weeks after sciatic nerve transection and repair is shown in panel B. Results from optically treated and untreated mice were compared. C. The ratio of the number of motoneurons in optically treated to untreated mice is shown as mean (<u>+</u>SEM) values. The results from both retrograde labeling methods indicate that more than twice as many motoneurons regenerated following optical treatment.