Fig. 5: Cyclin A2 (Ccna2) based ProTracer reveals a highly regional pattern of cardiomyocyte cell-cycle activity.

a Schematic showing generation of a Ccna2-CrexER knock-in allele. b Immunostaining for E-Cad, ESR, and EdU on intestinal sections from adult (10 weeks old) Ccna2-CrexER mice. Mice received intraperitoneal EdU injection and were sacrificed 3 h afterward for analysis. c Schematic showing AAV9-Dre induced genetic tracing of Ccna2⁺ cardiomyocytes. d Schematic of the experimental design. e Immunostaining for GFP and TNNI3 on heart sections prepared from AAV9-control-treated mice. f, g Immunostaining for GFP and TNNI3 on heart sections from AAV9-Dre treated mice. Numbered regions (1,2,3,4) are magnified on the right. Arrows, GFP⁺ cardiomyocytes. h Immunostaining for GFP and TNNI3 in transverse heart sections. The dotted line demarcates the inner core region of the LV that harbors the majority of GFP⁺ cardiomyocytes. Numbered regions (1–6) are magnified on the right. i Quantification of the distribution of GFP⁺ CMs in different regions of the ventricles. Data are the mean ± s.e.m.; n = 5. Scale bars: yellow, 1 mm; white, 100 µm. Each image is representative of five individual biological samples.