Figure 3.

LV (A) and RV (B) cell volumes were calculated and were best fit by bisegmental regression that showed increased growth in the neonatal segment (n = 79 fetuses and neonates were studied, of which only n = 75 LV and n = 74 RV had binucleated myocytes. LV and RV quadrinucleated myocytes were only measured in n = 15 of the neonates. At least 100 myocytes were measured per ventricle of each animal). C) The cardiomyocytes cell volume per nucleus increased rapidly in the postnatal segment. D) The slope of the relationship of binucleated and mononucleated myocyte volume between ventricles is not significantly different from 2 for the LV (n = 75) or RV (n = 74), indicating that cell volume is similarly regulated as a function of nuclei number in mononucleated and binucleated myocytes. Fetal data from Jonker et al. (3). Regression (solid) lines and 95% CI (dashed) best fit to each data set are shown; bars show 95% CI of the breakpoints. Regression data are included in Tables 1 and 2. bi, binucleate; mono, mononucleate.