Figure 8. TyrCre-driven RarαDN reduces enteric neuron number and causes abnormal ENS patterning.

(A–H) E13.5 RarαDN^LoxP/+; TyrCre⁺ or TyrCre⁺ (control) bowels stained with TuJ1 antibody (red) and DAPI. Scale bars: 1 mm (A and E). Boxes in A and E indicate regions of stomach (B and F), midgut (C and G), and distal colon (D and H) that are magnified in adjacent images. Scale bars: 50 μm (B–H). (I) RarαDN^LoxP/+; TyrCre⁺ appear similar to control (TyrCre⁺) at birth but did not feed and lack a milk spot in stomach (n = 6). (J) RarαDN^LoxP/+; TyrCre⁺ distal bowel appeared grossly similar to control (TyrCre⁺) at P0 (n = 10). (K) TdTomato⁺ images of proximal small intestine (PSI) and colon of either RarαDN^LoxP/+; TyrCre⁺ or TyrCre⁺ (control) E18.5 pups. Scale bar: 1 mm. (L) Whole-mount IHC of E18.5 RarαDN^LoxP/+; TyrCre⁺ or TyrCre⁺ (control) bowels using HuC/D (red) and NOS1 (green) antibodies and via TdTomato (blue) fluorescence. Scale bar: 100 μm. (M) All TdTomato⁺ cells in the small bowel and colon were HuC/D⁺ in E18.5 RarαDN^LoxP/+; TyrCre⁺ and TyrCre⁺ (control) mice. (N–S) Total HuC/D⁺ neurons were reduced in PSI, distal small intestine (DSI) and colon of RarαDN^LoxP/+; TyrCre⁺ mice (N–P), but the percentage of HuC/D⁺ neurons expressing NOS1 was increased in mutants (Q–S). n = 3, TyrCre⁺ (control); n = 3, RarαDN^LoxP/+; TyrCre⁺. Two-tailed unpaired Student’s t tests were used for statistics.