Figure 2. Cell-autonomous RAR signaling is required for ENS precursor colonization of fetal small bowel and colon.

(A and B) Representative images of bowel colonization by TuJ1⁺ enteric neurons (red) at E12.5. (A) Wnt1Cre⁺ controls have TuJ1⁺ cells throughout the bowel from esophagus to midcolon. (B) RarαDN^LoxP/+; Wnt1Cre⁺ mice only have TuJ1⁺ cells present in the esophagus and stomach. A white arrowhead shows the position of the most distal TuJ1⁺ cell or neurite in each image. Scale bars: 500 μm. (C–H) Representative E12.5 images of stomach, small intestine (SI), and colon show cells stained with TdTomato⁺ (red) and HuC/D (green) throughout the bowel in control (C–E), whereas TdTomato⁺- and HuC/D-stained cells are absent in SI and colon of RarαDN^LoxP/+; Wnt1Cre⁺ mice (F–H). (C–H) Scale bar: 150 μm. (I and J) Circles show the position of the most distal TdTomato⁺ ENS cell in control or RarαDN^LoxP/+; Wnt1Cre⁺ mice at E12.5. The line attached to each circle indicates a hypoganglionic zone in controls. n = 5 controls, n = 5 RarαDN^LoxP/+; Wnt1Cre⁺.