Abstract
Summary From the ultrastructural aspects of the myocardial cell in different types of heart overloading, several points concerning the adaptation of the myocardial cell were briefly summarized: the respective role of hypertrophy and hyperplasia in heart enlargement, the nature of the myofibrillar changes; the changes in the volume, number and size of mitochondria, and the dependence of the cellular lesions on the severity of the load.