CGRP expression is reduced in both the embryonic and adult Elp1 cKO ENS. A, Immunohistochemical staining for CGRP expression (red) is reduced in the adult Tuba1a-Cre;Elp1^loxp/loxp cKO ileum. B, Quantification of CGRP protein expression shows significant reductions in the adult cKO (B; unpaired t test p = 0.0227; n = 4). C, CGRP+ axons are also visually reduced in the villi mucosa in the adult cKO proximal duodenum. D, E, CGRP+ axons in cKO and control villi were quantified in (D) and while a trend is detected of reduction in the cKO, due to considerable variability in absolute numbers of immunolabeled axons between experiments in both controls and cKOs, a significant difference between genotypes was only revealed when the changes between genotypes was quantified in a single experiment; the experiment was repeated three times (E). The line connects the average axon number in the control and cKO in the same experiment. F, G, Quantification of CGRP expression in the embryonic Wnt1-cre;Elp1^loxp/loxp CKO rectum also shows significant reduction in CGRP innervation (unpaired t test p = 0.0497; n = 3).