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FIG. 3. Colocalization of X-msr signal and RLDx. Following in situ hybridization with an X-msr probe, embryos were embedded in wax, transversely sectioned, and then analyzed for the presence of both X-msr and RLDx. Black arrowheads (A, D, and G) indicate X-msr signal in anterior cardinal veins, endocardium, and posterior cardinal veins, respectively; white arrowheads (B, E, and H) indicate the same location when viewed under fluorescence. Black arrows (C, F, and I) show overlay of X-msr signal with fluorescence in the identical location. (A, B, and C) Examples of X-msr staining in the anterior cardinal veins colocalizing with RLDx from blastomere D2.2. (A) X-msr signal in anterior cardinal vein, (B) fluorescence in the same section, and (C) an overlay of both images showing colocalization. (D, E, and F) Examples of X-msr staining in the endocardium colocalizing with RLDx from blastomere D1.1. (D) X-msr signal, (E) fluorescence in the same section, and (F) an overlay of both images. Insets represent an enlargement of the upper left region of the endocardium showing X-msr signal (C), fluorescence (D), and overlay (E). Arrowheads in the insets point to two cells showing both X-msr signal and fluorescence; directly to the right of the asterisk is depicted a cell that shows X-msr signal but does not show fluorescence colocalization. (G, H, and I) Examples of X-msr signal in the posterior cardinal vein colocalizing with RLDx signal from blastomere V2.2. (G) X-msr signal, (H) fluorescence in the same section, and (I) an overlay of both images. For A, dorsal is toward the top of the page. Magnification for A is 250x, D is 400x, G and H is 200x, and I is 180x. Note that the magnification of G and H is slightly greater than that of I. (J) Schematic indicating planes of section: I (A, B, C), II (D, E, F), and III (G, H, I). Diagram adapted from Nieuwkoop and Faber (1967). acv, anterior cardinal vein; endo, endocardium; fg, foregut; mb, midbrain; myo, myocardium; nc, notochord; ret, retina; som, somite; pcv, posterior cardinal vein. |