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Amacronucleus (formerly also meganucleus) is the larger type ofnucleus inciliates.[1] Macronuclei arepolyploid and undergo direct division withoutmitosis. It controls the non-reproductive cell functions, such asmetabolism. During conjugation, the macronucleus disintegrates, and a new one is formed bykaryogamy of themicronuclei.
Macronuclei contain hundreds to thousands of chromosomes, each present in many copies.[2][3] There is no mechanism to precisely partition this complex genome equally during nuclear division; thus, how the cell manages to maintain a balanced genome after generations of divisions is unknown.
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