Inhibition of hedgehog (Shh) signaling by cyclopamine suppresses intestinal remodeling during
A: Cyclopamine-treated animals have longer intestine at the end of metamorphosis. Tadpoles at stage 58 were treated with vehicle (100% ethanol, final concentration in rearing water: 0.1%) (3 tadpoles) or tomatidine (7 tadpoles), or cyclopamine (8 tadpoles) till they reached stage 66. Intestinal length was measured from bile duct junction to colon for all animals. * indicated significant difference between the cyclopamine group and the other two groups (p < 0.05). Note that the cyclopamine-treated tadpoles completed metamorphosis, as judged based on external morphology, e.g., resorption of the tail, similarly as the animals in the tomatidine and vehicle groups. However, they had significant longer intestine. B: Retarded intestinal maturation in the cyclopamine-treated animals. Transverse sections of the intestine from the animals above were stained with methyl green pyronin Y (MGPY), which stained DNA in blue (methyl green) and RNA in red (pyronin Y). Note that the cyclopamine-treated animals had intestines with fewer and less structured epithelial folds as well as reduced connective tissue and muscles (outer layers). C: Immunofluorescence staining showing reduced intestinal muscle development in the cyclopamine-treated animals. The intestinal sections above were stained with anti-smooth muscle actin (SMA) antibody as well as DAPI for cell nuclei.