Frozen spinal cord sections (10 μm thick) were blocked and incubated in a cocktail of rabbit anti-TrkA and goat anti-TrkC antibodies (gift of Dr. Reichardt; Huang et al. 1999), followed by a cocktail of CY3 conjugated donkey anti-rabbit and FITC conjugated donkey anti-goat antibodies (Chemicon, Temecula, California, United States) in the presence of 0.3% TritonX-100 and 10% normal donkey serum.