title: Retrograde labeling of regenerating motor and sensory neurons using silicone caps.
abstract: BACKGROUND
  Retrograde labeling permits the investigation of the number, distribution and axonal projections of neurons in the peripheral nervous system. The well technique for labeling peripheral nerves consists of incubating the exposed peripheral nerve in a well for one hour, a time intensive technique. However, other techniques that inject tracers directly into the nerve or muscle may result in variable labeling depending on nerve preparation and location of injection.
  
  
  METHODS
  We describe a method of retrograde labeling peripheral nerves that increases tracer uptake and improves labeling efficiency. This technique utilizes a silicone cap over the nerve that is kept in place with fibrin glue, permitting closure of the incision with the cap in place, mitigating the need to wait one hour for back-labeling as with the standard well technique.
  
  
  RESULTS
  In the rat common peroneal nerve, the new silicone cap technique, compared to the standard well technique, labeled 405±11 (SEM) vs. 378±21 motoneurons and 953±40 vs. 948±57 sensory neurons. These counts were not statistically different. Labeling intensity was greater in DRG neurons with the silicone cap technique, but this difference was not evident in motoneurons.
  
  
  CONCLUSIONS
  Retrograde-labeling with silicone caps labels an equal number of motor and sensory neurons in comparison with the standard well technique and labels sensory neurons with greater intensity.
  
  
  CONCLUSIONS
  Retrograde-labeling with silicone caps reliably labels neurons and significantly decreases the time required for labeling, reducing anesthetic exposure and improving the efficiency of the technique.
authors.affiliation: Division of Plastic and Reconstructive Surgery, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Canada; Department of Surgery, Faculty of Medicine, University of Toronto, Canada. Electronic address: joseph.catapano@utoronto.ca.
authors.forename: Joseph
authors.initials: J
authors.lastname: Catapano
authors.affiliation: Division of Plastic and Reconstructive Surgery, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Willand
authors.affiliation: Division of Plastic and Reconstructive Surgery, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada.
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Zhang
authors.affiliation: Division of Plastic and Reconstructive Surgery, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Scholl
authors.affiliation: Division of Plastic and Reconstructive Surgery, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada.
authors.forename: Tessa
authors.initials: T
authors.lastname: Gordon
authors.affiliation: Division of Plastic and Reconstructive Surgery, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Canada; Department of Surgery, Faculty of Medicine, University of Toronto, Canada.
authors.forename: Gregory H
authors.initials: GH
authors.lastname: Borschel
mesh_terms: D000818:Animals; D005456:Fluorescent Dyes; D005727:Ganglia, Spinal; D008297:Male; D009046:Motor Neurons; D009416:Nerve Regeneration / Q000502:physiology*; D010543:Peroneal Nerve / Q000293:injuries; D051381:Rats; D017207:Rats, Sprague-Dawley; D011984:Sensory Receptor Cells; D013194:Staining and Labeling / Q000379:methods*; D013266:Stilbamidines
chemical_list: C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D005456:Fluorescent Dyes; D013266:Stilbamidines
keywords: Axons; Fluorescent dyes; Fluorogold; Peripheral nerve injuries