pdip expression is undetectable in X. tropicalis ptf1a/p48-null mutant tadpoles. Whole-mount in situ hybridization analysis of pdip expression in F2 X. tropicalis ptf1a/p48 mutant tadpoles (stage 43). Ventral-lateral view, head to the left. (A, C) About 22% homozygous tadpoles showed complete absence of pdip expression. (B, D) The remainder uniformly showed strong pdip expression, suggesting normal pancreas development in ptf1a/p48 heterozygous tadpoles.