Figure 1.

Diagram of the experimental procedure used to label motoneurons. Mice were treated with blank or estradiol filled capsules immediately prior to nerve transection and repair surgery. Mice then were treated with no exercise or were treadmill trained using a continuous (males) or interval (females) paradigm for 5 days per week for 2 weeks. Two weeks after the nerve transection and repair surgery, neurons were labeled using retrograde tracers applied 1.5mm distal to the original lesion site. Three days later, mice were euthanized and tissue was harvested for histologic analysis. Motoneurons labeled with dye were counted to measure the number of motoneurons participating in axon regeneration.