Fig 2: TRPV3 is expressed in basal layers of oral epithelium. Left column, Tuj1 anti-ßIII tubulin (all afferent neurons). Second column, Anti-NFH antibody (myelinated neurons). Third column, Anti-TRPV3 antibody. Right column, Merge with TRP immunoreactivity in yellow, ßIII immunoreactivity in cyan, NFH immunoreactivity in magenta. Dashed line indicates epithelia-lamina propria border. A, TRPV3 expression was found in basal epithelial layers of the hard palate as well as in the lamina propria. White arrows denote areas where Merkel cells typically concentrate (Moayedi et al., 2021). Note that Merkel cell afferents are visible with ßIII tubulin staining in cyan. B, TRPV3 immunoreactivity was dispersed throughout fungiform epithelium. C, TRPV3 expression was found in basal epithelium of filiform papilla. A TRPV3 negative end bulb of Krause (arrow) is found within the lamina propria of the filiform papilla visualized with expression of ßIII tubulin and NFH.

Fig 3: Antigen blocking shows specificity of TRP antibodies. A, TRPV3 immunoreactivity was identified in the foreskin epithelium. Antigen pretreatment blocked TRPV3 immunoreactivity (N = 3 foreskins, paired t test p = 0.022). B, TRPV4 immunoreactivity was identified in the foreskin epithelium and was diminished with antigen pretreatment (N = 7 foreskins, Wilcoxon matched pairs signed-rank test p = 0.016). Note, removal of outlier data point results in p = 0.02. C, TRPA1 immunoreactivity was identified primarily in the dermal compartment of foreskin tissue and was completely ablated with antigen pretreatment (N = 4 foreskins or tongues, paired t test, p = 0.0016). D, TRPM8 immunoreactivity was localized primarily to the foreskin epithelium and portions of the dermal compartment. Antigen blocking greatly diminished immunoreactivity (N = 3 foreskins, paired t test, N = 0.04). E, TRPV1 immunoreactivity was found primarily in intraepithelial nerve fibers of the foreskin. Antigen pretreatment completely abolished TRPV1 nerve fiber immunoreactivity but not the diffuse TRPV1 immunoreactivity of epithelial cells (N = 3 foreskins, paired t test, N = 0.0004). All graphs show mean ± standard deviation.