This protocol is used for studies of neurons containing retrograde tracer dye in adult rat dorsal root ganglia (DRG) or pelvic ganglia (PG; synonym, major pelvic ganglia). Cryosections of ganglia are mounted directly on slides for immunohistochemical staining. Antibodies have been selected to distinguish different neurochemical classes of PG neurons or to specifically identify subclasses of sensory neurons that are myelinated (immunoreactive for NF200 [neurofilament, 200 kD]) or nociceptive (immunoreactive for TRPV1).