Extracellular labeling of unmyelinated dorsal root terminals after WGA-HRP injections in spinal ganglia.
Wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) is a widely used neuroanatomical tracer. When compared with other tracers, WGA-HRP may preferentially label unmyelinated fibers. In agreement with this hypothesis, injections of WGA-HRP in cervical and lumbar dorsal root ganglia resulted in more prominent light microscopical labeling in superficial than deep laminae of the dorsal horn. However, ultrastructural examination of these laminae reveals a paucity of terminal labeling in contrast to the abundance of extracellular tracer in the space surrounding unmyelinated fibers and their terminals, and to the widespread occurrence of transneuronal labeling. These results bear upon the mechanism of preferential labeling in the spinal cord and have implications for the interpretation of the labeling obtained when using WGA-HRP.
Department of Cell Biology and Anatomy, University of North Carolina, Chapel Hill 27599-7090.
R J
RJ
Weinberg
D J
DJ
Tracey
A
A
Rustioni
D000818:Animals; D001370:Axonal Transport; D005727:Ganglia, Spinal / Q000033:anatomy & histology* / Q000648:ultrastructure; D006735:Horseradish Peroxidase; D008854:Microscopy, Electron; D009412:Nerve Fibers / Q000648:ultrastructure*; D051381:Rats; D011919:Rats, Inbred Strains; D013126:Spinal Nerve Roots / Q000033:anatomy & histology* / Q000648:ultrastructure; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins
D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins; D006735:Horseradish Peroxidase