Figure 4.

The hypertrophic nerve fibers in the distal gut of GFRa1 hypomorphic mice are cholinergic. (A) Acetylcholinesterase histochemistry at P10 showing similar innervation in the duodenum, as well as cholinergic hypertrophic nerve fibers characteristic of HSCR in the colon of Gfra1^hypo/hypo mice. In the ileum, an image distal of the point of dilatation is shown (N = 3 animals per genotype). (B) Quantification of the acetylcholinesterase-positive plexus area in P10 WT and Gfra1^hypo/hypo mice (N = 3 animals per genotype, ***P < .001). (C) NADPH diaphorase histochemistry for nitric oxide synthase (NOS)-positive neurons in P10 mice showing similar innervation in the duodenum and an absence of NOS-positive innervation in the colon of Gfra1^hypo/hypo mice; N = 4–5 animals per genotype (N = 2 animals per genotype for the colon). (D) Quantification of NOS-positive plexus area in P10 WT and Gfra1^hypo/hypo mice; N = 4–5 animals per genotype (N = 2 animals per genotype for the colon). Analysis of variance and the Tukey multiple comparisons tests were used for statistical analysis. n.a., not applicable for Gfra1^hypo/hypo mice. ACE, acetylcholinesterase; dist, distal; prox, proximal (data are presented as means ± SEM). All summary data are presented as means ± SEM. ∗P < .05, ∗∗P < .01, and ∗∗∗P < .001.