text: Mice were briefly anesthetized during the procedure, induced with 
  3% to 5% isoflurane, and then maintained at 1.5% to 2% as required. 
  Hindlimbs were taped with the plantar surface of the paw facing up, 
  and a custom, 26G removable needle with a 30˚ bevel, attached to 
  a 25-mL Hamilton syringe, was inserted between the 2 distal-most 
  footpads, towards the medial aspect of the hindpaw. The needle 
  was then rotated 90˚, so the bevel faced medially. Furthermore, 4-mL 
  FastBlue (FB; 2% in sterile phosphate-buffered saline (PBS); CAS# 
  73819-41-7; Polysciences, Inc, Warrington, PA) per paw was then 
  slowly injected, and the needle was left in place for 10 seconds, 
  before rotating and carefully retracting to avoid backflow of FB along 
  the needle track. This prevented the FB bolus from contacting the 
  sural innervation territory of the lateral hindpaw, restricting it largely to 
  the tibial innervation territory of the glabrous hindpaw skin. 