Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
in many plants and some animals, doubling of the number of chromosomes in the nuclei of cells.
In contrast to mitosis, the nuclear membrane and the nucleolus are not destroyed, the cleavage spindle does not form, and reorganization of the cytoplasm does not occur. However, the chromosomes do go through the cycle of spiralization and despiralization. Repeated endomitoses lead to the development of giant polyploid nuclei, resulting in an increase of deoxyribonucleic acid (DNA) in the cell. The term “endomitosis” also denotes the process of repeated doubling of the nucleoprotein threads (chromonemata), which constitute the core of the chromosomes, without an increase in the number of the chromosomes. As a result of the substantial increase in the amount of DNA in the nuclei, giant (polytenic) chromosomes form.