Fig. 2. ENS defects in ß1 integrin conditional mutants. (A-F) Whole-mount X-Gal staining. (A,B) E12.5 guts. Black arrowheads indicate the position of the ENCC migratory front. The control hindgut is being invaded, whereas the mutant ENCC front is still located in the proximal caecum. Insets show higher magnification of distal midguts. ENCCs have a scattered distribution in the control but form clusters in the mutant. (C,D) E16.5 guts. The mutant ENCCs have stopped in the middle of the hindgut, whereas control ENCCs have reached the rectum (black arrowheads). (E,F) Descending colon at P14, with higher magnification in insets. Aganglionosis occurs in the mutant, with abnormal extrinsic innervation, compared with the control regular network. (G,H) Freshly dissected P4 guts. The mutant ascending colon and caecum are distended (megacolon) compared with control. (J-O) Whole-mount X-Gal staining of small intestines at E16.5 (J,K), P1 (L,M) and P14 (N,O). Mutant ENCCs form abnormal aggregates surrounded by ENCC-free spaces, compared with the regular ganglia network in the control. (P,Q) Confocal images of a whole-mount immunostaining on P14 small intestines with anti-NF160 (red) and anti-S100 (green) antibodies, recognising neuronal processes and glial cells, respectively. Green and red arrows in P indicate the circular and longitudinal orientations of the samples, respectively. Green and red arrowheads show control ganglia and neuronal processes following the circular and longitudinal directions, respectively. In the mutant, ganglia and neuronal processes do not follow these directions. ac, ascending colon; caec, caecum; dc, descending colon; dsi, distal small intestine; hg, hindgut; mg, midgut. Scale bar: 500 µm in B,D,K; 2 mm in F; 1 mm in M,O.