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Abstract:
"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.
Insights
Amitosis, or direct cell division, is a misinterpretation of incomplete mitosis. Binucleate cells in tissues like the myocardium result from inhibited cell division, not amitosis.
Area of Science:
- Cell Biology
- Histology
- Developmental Biology
Background:
- The concept of amitosis, or direct cell division, has been debated for over a century.
- Historically, many observed instances of amitosis have been attributed to misinterpretations of nuclear division processes.
Purpose of the Study:
- To re-evaluate the phenomenon of amitosis, particularly in the context of binucleate cell formation in the myocardium.
- To clarify the mechanisms underlying the formation of binucleate cells and restitution nuclei.
Main Methods:
- Review of historical literature on amitosis.
- Microscopic examination of myocardial tissue, including postnatal pig hearts with immediate fixation.
- Analysis of mitotic indices at different postnatal ages.
Main Results:
- Most previously described cases of amitosis are actually incomplete mitoses.
- Binucleate cells and restitution nuclei result from mitotic inhibition, which is more prevalent in differentiated tissues.
- Mitoses are observable in postnatal pig myocardium with immediate fixation, showing a decline in mitotic index with age.
- Delayed fixation leads to degenerated nuclear stages, mimicking amitosis.
Conclusions:
- The formation of binucleate myocardial cells and nuclear rows is a consequence of mitosis with impeded cellular division, not amitosis.
- The historical interpretation of amitosis in certain tissues is a methodological misinterpretation.