Regeneration of myocardial cells. Observation in aneurysmectomized ventricular wall.

A small necrotic focus with regeneration of myocardial cells in an aneurysmectomized ventricular wall was observed in a 46-year-old man. Marginating the area of necrosis were myocardial cells with mitosis, with frequent multinucleated and binucleated cells. In the area of necrosis, there was a proliferation of many round, oval to polygonal cells with a high mitotic activity. These cells had eosinophilic granular cytoplasm and one prominent nucleus. Some cells were solitary while others clustered in and around the damaged myocardial fibers. Some cells formed a syncytium and were attached to the perimysial tubes with protoplasmic extensions. These proliferated cells are believed to be a single-cell line and to originate from the damaged myocardial cells. This observation suggests that human myocardial cells may regenerate continuously from surviving myocardial cells and proliferate discontinuously.