Table 1.

Number of retrogradely labeled spinal motoneurons.

Animal groups	DiI-labeled neurons innervating dorsiflexor muscles	FB-labeled neurons innervating plantar flexor muscles	Double-labeled neurons	Total (DiI+FB)	Number of neurons (% of normal count)
Normal rats*	443 ± 74	106 ± 23	Zero	549 ± 83	100%
Run–idle	352 ± 139	126 ± 53	37 ± 28	515 ± 193	93.9%
Run–run	379 ± 99	86 ± 36	10 ± 5	476 ± 99	86.6%
Idle–idle	364 ± 54	101 ± 39	15 ± 10	480 ± 94	87.4%
Idle–run	352 ± 68	85 ± 23	10 ± 7	453 ± 76	82.4%

DiI-labeled motoneurons of the dorsiflexor muscles projecting through the common fibular nerve and Fast Blue-labeled motoneurons of the plantar flexor muscles projecting through the soleus nerve in untreated animals and rats that had or had not received 12 weeks of treadmill-training before and/or after sciatic nerve graft (mean ± SD). Double-labeled motoneurons innervating dorsiflexor and plantar flexor muscles at the same time (mis-sprouting) were found in all rats that had received nerve surgery but not in intact animals. The right column shows the total number of motoneurons that were regenerated 91 days after nerve surgery.

^*Our previous data from six normal Lewis rats (5).