In vivo differentiation of EMT-induced XtiSCs into cardiomyocytes. (a) Experimental scheme. RFP-positive XtiSCs were cultured in a growth medium supplemented with 3 μM CHIR99021 or 0.1% DMSO as a control for 3-4 days before transplantation into 2-day-old tadpoles. (b) At the 4th, 14th, or 30th day postinjection (dpi), tadpoles were fixed and sectioned for double staining with antibodies against red fluorescent protein and cardiac troponin T labeling cardiomyocytes in the heart. Scale bar: 20 μm. Nuclei stained with DAPI. Results are representative of four biological replicates.