Culture and identification of mouse primary cardiomyocytes. (a) After 48 h of incubation, adherent cardiomyocytes accounted for approximately 90% of the cells. The cells exhibited various morphologies, such as spindle and polygonal shapes. After 72 h of incubation, the cells fused together (10×). (b) Cardiomyocytes identification using cTnI immunofluorescent staining (10×).