Figure 1.
Intramuscular injections of retrograde tracer were used to identify motoneurons innervating the medial and lateral gastrocnemius (MG/LG). Only MG/LG motoneurons were selected for quantitative analysis in this study. Yellow arrow points to a population of motoneuron somas in the lateral lamina IX in the ventral horn of spinal cord segment L5 containing cholera toxin subunit B (CTB) conjugated to 488 fluorophore (green), one of the retrograde tracers used in this study. Nissl-IR (White) was used as a general neuronal stain. Retrogradely labeled cells selected for quantitative analysis were located in appropriate position within the motoneuron pool consistent with previous reports identifying location of MG/LG motoneuron somas (Romanes, 1951). For every injured αMN a contralateral control αMN was also selected from the appropriate position within lamina IX (see sec 4.4 methods) Scale bar is 200 μm.