Amitosis

Amitosis, also known as karyostenosis, direct cell division, or binary fission, is a form of asexual cell division primarily observed in bacteria and other prokaryotes. This process is distinct from other cell division mechanisms such as mitosis and meiosis, mainly because it bypasses the complexities associated with the mitotic apparatus, such as spindle formation. Additionally, amitosis does not involve the condensation of chromatin into distinct chromosomes before the cell divides, thereby simplifying the process of cellular replication.

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.