Figure 1.

Mrgprd^Cre lineage afferents, which comprise Mrgprd, Mrgpra3, and Sst populations, target lamina IIi in the dorsal horn and the superficial aspect of the skin. (A–E) Representative images of a lumbar dorsal root ganglion from a Mrgprd^Cre; Ai32 mouse that is costained for eYFP and IB4 or CGRP. (F–J) Representative images of the superficial dorsal horn, lumbar level from a Mrgprd^Cre; Ai32 mouse that is costained for eYFP and IB4 or CGRP. (K–M) Representative images of the glabrous skin from a Mrgprd^Cre; Ai32 mouse that is costained for eYFP and PGP9.5. Dotted line demarcates the epidermal–dermal junction. (N–P) Representative RNA FISH images of lumbar dorsal root ganglion from a Mrgprd^Cre; Ai32 mouse that is costained with probes against Eyfp, Mrgprd, Mrgpra3, and Sst. (Q) The relative proportion of primary afferent populations captured by the Mrgprd^Cre lineage as determined by FISH. Data are from 3 mice, with 4 to 5 slices imaged per mouse for a total of 692 Mrgprd^Cre lineage neurons counted per probe combination. (R) Expression of Mrgprd, Mrgpra3, and Sst mRNA relative to Gapdh in individual eYFP-marked Mrgprd^Cre lineage neurons. Data are presented as the log₂ ΔCT expression relative to Gapdh expression within the same cell such that smaller numbers represent higher mRNA expression. Colored dots represent data points from individual cells from a single, representative mouse. (S) Schematic to illustrate the different subtypes of cutaneous C fibers that are captured by the Mrgprd^Cre and Trpv1^Cre alleles with developmental (lineage) or adult recombination. FISH, fluorescence in situ hybridization.