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. Author manuscript; available in PMC: 2021 Feb 10.
Published in final edited form as: Dev Cell. 2020 Jan 9;52(3):350–363.e6. doi: 10.1016/j.devcel.2019.12.006

Figure 1. Clonal analysis and lineage tracing identify arterial mesothelial cell-related lineages and their separation from epicardium.

Figure 1.

(A) Whole-mount ventral view of a specimen with a mesothelial clone in the PA. (B) Whole-mount ventral view of a specimen with an epicardial clone over the sub-pulmonary myocardium. (B’) high magnification of the OFT area of the specimen in B. (C) Distribution of Clonal Analysis specimens according to the presence AMCs and EPICs clones and their color. (D–G’’) Distribution and fate of CreERT2-expressing cells in Wt1CreERT2 embryos. Images show the expression of CreERT2 in the pericardial cavity of E9 (E-E’’) and E10 (G-G’’) embryos and the distribution at E14.5 of cells recombined in Wt1CreERT2 embryos upon TM injections at E8.5 (D) and E9.5 (F). (E’-E’’) and (G’–G’’) show magnifications of the boxed areas in E and G, respectively. Dotted lines in D and F indicate the approximate limit between the PA and the RV. (H–J’) Whole-mount examples of clonal contributions to the base of the great arteries and the sub-arterial regions of the ventricles, and schemes showing the lineages identified. (H’’-I’’’) Sections of specimens in (H’–I’) showing co-localization of clonally labelled cells with markers of smooth muscle (H’’, I’’) and epicardium (J’’’). Asterisks indicate equivalent positions at the mesothelial side of the whole-mounts, schemes and sections. White arrowhead in H’’ shows cells with co-localization of EYFP and SM22α. Black arrowhead in H’’ shows an arterial endothelial cell positive for EYFP and negative for SM22α. (K, L), tables scoring the results of clones containing AMCs in the Aorta (K) and PA (L) by specimen and position of the AMCs. The upper row indicates the contribution to AMCs and EPICs, according to the color code in H-J. The lower rows indicate the presence of additional cell lineages in the scored clones and their clonal label (LacZ or EYFP). All scale bars: 100µm. Ao: Aorta; PA: Pulmonary artery; RA: Right atrium; RV: Right ventricle; LV: Left ventricle; TnT: cardiac Troponin T; ER: estrogen receptor; Fb: Fibroblast; SM: Smooth muscle; Ms: Mesothelium; valv: valvular mesenchyme; BIL: Blood island-like coronary structure; CM: Cardiomyocyte; EPICs: epicardial cells; EC: Endothelial cell. See also Figures S1 and S2.