Ablation of fibroblasts in the perinatal proliferative window. (A) Experimental scheme. (B-C) 4 chamber view of (B) tdTomato and (C) Col1a1-GFP expression in control and ablated hearts. Ao: aorta, LA: left atria, RA: right atria, LV: left ventricle, RV: right ventricle, IVS: interventricular septum. (D-G) Representative images of (D) tdTomato, (E) PDGFRα, (F) isolectin B4 (IB4), and (G) αSMA immunostaining in the LV myocardium. Asterisks indicate blood vessels. Representative from a minimum of 3 biological replicates for each staining. (H) qPCR analysis of selected fibroblast, ECM, and alternative fibroblast genes in whole ventricle tissue from ablated hearts compared to controls. 18 s was used as a housekeeping gene. Control: n = 3; ablated: n = 6. Results are mean ± SD.