[Regeneration of the myocardium of fetuses and newborn rabbits].

The work is devoted to studies of regeneration of the myocardium in fetuses and newborns of rabbits after a mechanical trauma of the heart. It was established that in fetuses under natural conditions of the alive organism instead of the perished tissue of the myocardium during the period of 5-8 days there developed a wholesome transverse-striated musculature whose fibers contained glycogen and redox enzymes. In newborn rabbits the defect of the myocardium was replaced by a mature fibrous connective tissue, regeneration was accomplished at the expence of hyperplasia of intracellular ultrastructures. The loss by the heart muscular tissue of the capacity for complete regeneration takes place within the 24th day of the intrauterine development and the 1st day of life.