Ultrastructural Features of Left Ventricle Cardiomyocytes in Preterm Newborn Rats

The structure of left ventricular cardiomyocytes of 1 day preterm newborn rats was studied using transmission electron microscopy. It was shown that the relative area of the nucleus in cardiomyocytes of preterm rats is lower, and the relative area of the cytoplasm is higher than in full-term rats, while the relative areas of myofibrils and mitochondria do not differ. In cardiomyocytes of preterm rats damaged mitochondria, subsegmental myofibrillar contracture, and cytoplasmic swelling were found on the first postnatal day. Preterm birth in rats, in contrast to birth at term, is accompanied by the development of a number of ultrastructural damages in cardiomyocytes.