Fig. 1.

Mouse and zebrafish homologues of rfx2 are expressed in ciliated organs of asymmetry and other ciliated tissues. In situ localization of mouse Rfx2 transcripts indicated no expression in late streak (LS) or earlier stage embryos (A). Expression was first detected in the posterior notochord (PNC) at late headfold stage (B), persists in the midline through e8.5 (C) and was downregulated in all but the posterior tail by e9.5 (D). In situ localization of zebrafish rfx2 indicated that transcripts are present maternally (E). At shield stage zygotic expression was limited to mesendoderm at the margin and dorsal forerunner cells (DFC) (F). During late epibiloy (G) and bud stages (H) rfx2 transcripts are restricted to the embryonic midline. During somite stages, expression was restricted to the neural tube (NT) and pronephric ducts (PND) (I,J) and becomes down-regulated everywhere except regions of the dorsal brain by 40 hr post-fertilization (K).