Table 1.

Perinatal remodeling: a list of the main changes in cardiomyocytes during the transition from the prenatal to the postnatal phenotype.

	Prenatal heart	Postnatal heart
Number of nuclei	1 nucleus	1-2 nuclei
Main source of energy	Glycolysis	Oxidative phosphorylation
Mitochondria	Small, immature	Large, with dense cristae
Myofibrils	Poorly organized β-myosin heavy chain Slow skeletal muscle isoforms	Organized along the long axes α-myosin heavy chain Cardiac muscle isoforms
Adherence junctions	Surround the cells	Organized at the site of myofibril attachment