Amitosis

Amitosis, also known as karyostenosis, direct cell division, or binary fission, is a form of asexual cell division that occurs in most prokaryotes. It differs from other forms of cell division (e.g., mitosis, meiosis) as it does not involve the mitotic apparatus (spindle formation) or the condensation of chromatin into chromosomes prior to cellular division.

Several instances of cell division previously thought to be "non-mitotic", such as the division of some unicellular eukaryotes, may actually occur by "closed mitosis", which differs from open or semi-closed mitotic processes. These processes involve mitotic chromosomes and are classified based on the condition of the nuclear envelope. Amitosis can also affect the distribution of human lactic acid dehydrogenase isoenzymes, which are present in almost all body tissues. An example of amitosis is spermatogenesis. During amitosis, the cell membrane does not divide.

Cells containing two or more nuclei are called binucleated and multinucleated cells, respectively, which can also result from the fusion of cells. Although amitosis differs fundamentally from mitosis without cytokinesis, some similarities exist between amitosis and cell fusion. Amitosis can result in nearly haploid nuclei, which is not possible through mitosis or cell fusion.