Nuclear and cellular size of myocytes in different segments of the developing rat heart

Abstract

The increase of the cellular volume in the segments sinus venosus and sinu-atrial junction seems to be due to a late differentiation process. In general, however, the increase of the myocardial volume in the individual cardiac segments is caused by hyperplasia of the cardiomyocytes in these segments and not by hypertrophy. The surface area of cells has a fixed relationship with cell volume, indicating that no important changes take place in the developmental period studied.