Fig. 1

Polaris and pkd2 are expressed in multiple ciliated tissues during early development. In situ localization of polaris (A–I) and pkd2 (J–R) transcripts at early cleavage through 72 hpf (all panels are lateral views except panels C, G, I, and P, dorsal views, and panel R, ventral view). Maternal polaris RNA is present in cleavage stage embryos (A) and becomes undetectable by early gastrula stages (B). At late gastrula stages (C), polaris expression is restricted to dorsal forerunner cells (dfc) which later aggregate to form the primordium of Kupffer′s vesicle (Kv) at the end of gastrulation (D). Polaris expression is ubiquitous at later stages with high levels detected in the otic vesicle (ov) (F), the pronephric duct primordia (pnd) and floorplate (fp) (G). At 24 hpf, polaris is expressed in the brain and in the caudal floorplate (H). At 3 dpf, polaris is expressed in the brain (I). Maternal pkd2 message is not detected by in situ hybridization (J). At 40% epiboly, zygotic expression is detected in a band of 3–4 cell diameters at the blastoderm margin (K). Pkd2 RNA is localized to the hypoblast of the dorsal midline and to DFCs during gastrulation (L). From tailbud stage through 24 hpf, pkd2 is ubiquitous with higher levels of expression in KV (M) that persist to the 6 somite stage (N). pkd2 message is also detected in the pronephric duct primordia and floorplate (P) and at 24 hpf is highly expressed in the brain (Q). At 3 dpf, pkd2 is expressed in the pharyngeal arches (pa) and pectoral fins (pf) (R).