Snai2 expression is restricted to the connective tissue and peaks at the climax of intestinal metamorphosis. A: Snai2 mRNA level peaks at the climax (Stage 62). Quantitative RT-PCR analysis of Snai2 mRNA level in intestine from tadpoles at indicated stages, normalized against the control gene EF1a. B-G: In situ hybridization reveals connective tissue-specific expression of Snai2 in intestine. Note that high levels of Snai2 mRNA were detected fairly uniformly in the connective tissue at the climax (St61-62). H-I: Snai2 is not expressed in the muscle layers. In situ hybridization sections of Snai2 at the stage 61 were double-stained with smooth muscle actin antibody (red) to label the muscle layers (Ms). Ty: typhlosole, the single epithelial fold in in premetamorphic tadpole intestine where connective tissue is abundant; Lu: lumen; Ep: epithelium. Note that Snai2 labeled cells are localized between epithelium and muscle layers.