Peptidergic nociceptive axon visualization in whole-mount preparations of cornea and tympanic membrane in rat

A whole-mount preparation is described for visualizing unmyelinated peptide immunoreactive axons in two specialized tissues, thin enough for tracing axons to their terminal knobs. These tissues, the cornea and the mucosal surface of the tympanic membrane, are known to possess specialized nociceptor innervation and can be used for selecting sensory endings labeled by peroxidase reaction product and embedded in plastic for more detailed analysis. Rat calcitonin gene-related peptide antibody proved a particularly robust primary antibody found in a substantial proportion of sensory unmyelinated axons in a variety of fixation and preparative conditions.