Fig. 1

Fig. 1. noi affects multiple aspects of pronephric development. (A-C) Pattern of pax2.1 expression in the pronephros during wild-type development. Whole-mount in situ hybridization using the pax2.1 antisense probe on (A) 12 somite, (B) 24 hpf and (C) 30 hpf wildtype embryos. pax2.1 is first expressed in intermediate mesoderm (A), and then pax2.1 expression is maintained in anterior duct (black arrows in B) and forming cloaca (arrowhead in B). Later, pax2.1 is transiently expressed in forming pronephric tubules (arrows in C). Transverse histological sections of (D-F) wildtype and (G-I) noi- mutant embryos at (E,H) 36 hpf and (D,F,G,I) 3 dpf. In wild type, tubules extend laterally from a medial glomerulus and pronephric duct (D). In noi- mutants, pronephric tubules are missing even though a midline glomerulus is seen (G). Pronephric duct is not seen at this level of section. Wild-type pronephric ducts (arrows in E) have well-formed epithelial cells and a small central lumen. In noi-, the pronephric ducts (arrows) are distended and epithelia appear flattened (H). Sagittal histological section of wildtype pronephric cloaca shows cuboidal epithelial cells and a central lumen (F). Cloaca morphogenesis in noi^tu29 is affected (I). Epithelial cells are flattened and the lumen is greatly distended. Note the lumen does open to the outside.