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FIG. 3 Expression of the tinman-related homeodomain sequence, XNkx-2.5 in RA-treated embryos. XNkx-2.5 sequences were detected by whole-mount in situ hybridization. (A) RA treatment was initiated at stage 20/21 and embryos were assayed at stage 24. Control embryo is on the left. Note the loss of Nkx-2.5 expression from the cardiac precursor region but not from the pharyngeal region. (B) Control embryo assayed at stage 32, after the onset of myocardial marker expression. The folding heart tube (ht) and thpharyngeal region (ph) are indicated. (C) RA-treated embryo assayed at stage 32. Note that XNkx-2.5 transcripts are detected in the pharyngeal region (ph) but not in the region of the heart tube (ht). |