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FIG. 5. RA treatment of heart region explants. Explants of the presumptive cardiac region were taken from normal embryos at stage 20/21 and cultured until stage 33/34, well after the time of cardiac differentiation. In all panels, differentiated myocardial tissue is detected by whole-mount in situ hybridization to XTnIc transcripts. The fate of the explanted region can be seen by comparing a normal embryo (A), to a similar embryo from which the presumptive cardiac region has been removed (B). Control explants differentiate to form cardiac tissue (C), while explants incubated in 1 mM RA exhibit no detectable cardiac troponin I expression (D). |
