Fig. 3. fos-1 loss-of-function causes abnormal uterine morphology and absence of uterine egl-13 expression. (A) Specification and mid L4 stage expression of egl-13::GFP(tyIs4) in the wild type and fos-1(ar105). fos-1(ar105) do not express GFP in uterine tissue (dashed ovals indicate where fluorescence was expected; fluorescent nuclei in the wild type are bracketed). The mid L4 stage uterus in ar105 is undifferentiated by comparison with the wild type, as apparent by the absence of a uterine lumen. Arrow indicates the utse, observed only in the wild type. Other GFP-positive cell bodies belong to the body wall, where fluorescence is not affected. (B) No uterine egl-13::GFP expression or lumen is observed after fos-1 RNAi treatment. Scale bar: 10 µm.