Amitosis: a historical misinterpretation?

"The problem of amitosis" (Bucher, 1971) has historical, theoretical, formal, and methodological aspects. Most cases of amitosis described during the past 125 years have proved to be misinterpretations of incomplete mitoses. Binucleate cells and occasionally dumbbell-shaped restitution nuclei are formed as the result of mitotic inhibitions, which increases with tissue differentiation. Until recently, binucleate cells in the myocardium have been interpreted as products of amitotic nuclear divisions, since mitoses are not found in human myocardium. However, mitoses are found in postnatal pig hearts fixed immediately after death. The mitotic index declines from 2.2% at day ten to 0.3% at day thirty during postnatal life. Delayed fixation yields degenerated prophase and telophase nuclei only. Thus the formation of binucleate myocardial cells and nuclear rows is the result of mitoses with impeded cellular divisions. To call these findings examples of amitosis is a misinterpretation.