Fig. 1.

Phenotypes of working cardiomyocytes, their proliferative potential and their changing prevalence in common model organisms. Percentages were obtained from studies that used microscopy methods for quantifying cardiomyocyte phenotypes. The prevalence of the different cardiomyocyte phenotypes in humans was taken from Mollova et al. (2013) and Bergmann et al. (2015). In humans with tetralogy of Fallot, a type of congenital heart disease, multi-nucleated cardiomyocytes (>2 nuclei) appear after the first month of life and persist into adulthood (Liu et al., 2019). Although the work of Adler et al. (1996) has served as an important reference for pig data, the results were obtained using an indirect approach. Consequently, recent results from isolated pig cardiomyocytes (Velayutham et al., 2020), using single-cell microscopy, are shown. The values for mouse were taken from Alkass et al. (2015), although nuclear ploidy in mono- and bi-nucleated cardiomyocytes was not clearly distinguished, and from Han et al. (2020). Values for zebrafish were taken from Wills et al. (2008) and González-Rosa et al. (2018).