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Figure 4. Decreased expression of myotome markers, decreased segmentation, and loss of hypaxial muscle in FRG1-depleted embryos. A,B: Stage 18 embryos injected (i, injected side) with either 40 ng of FMO1 or 40 ng of CMO respectively, stained for pax3 (dm dermomytome). C: Transverse section of a pax3-stained embryo injected with 40 ng of FMO1 showing less organized pax3 expression on the injected side (i) in the dermomyotome (arrowheads). D,E: myoD staining of stage 18 embryos injected with 20 ng of FMO1 and 40 ng of CMO, respectively. F: Graph showing percent stage 20 embryos with reduced pax3 in the dermomyotome and diffuse myoD staining. G,H: pax3 staining of injected (i) and uninjected sides of stage 34 embryos injected with 20 ng of FMO1, with close-up view of hypaxial muscle region. J,K: myoD staining of injected and uninjected sides of stage 34 embryos injected with 20 ng of FMO1. I,L: pax3 and myoD staining, respectively, of embryos injected with 40 ng of CMO. M,N: Vimentin antibody staining of injected (20 ng of FMO1) and uninjected side embryo (pm, pronephric mesenchyme). O: Percentage of embryos with defects in segmentation, hypaxial muscle, and mesenchyme with total numbers of embryos analyzed above each bar. P: Embryo injected with 40 ng of FMO1 and probed for myf5 shows no change in myf5 expression levels, despite a clear reduction in myotome width (double head arrow). |