Karyorrhexis (from

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

κάρυον ''karyon'', "kernel, seed or nucleus", and ῥῆξις ''rhexis'', "bursting") is the destructive fragmentation of the

nucleus Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to: * Atomic nucleus, the very dense central region of an atom *Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucl ...

of a dying

cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...

whereby its chromatin is distributed irregularly throughout the cytoplasm. It is usually preceded by pyknosis and can occur as a result of either

programmed cell death Programmed cell death (PCD; sometimes referred to as cellular suicide) is the death of a cell (biology), cell as a result of events inside of a cell, such as apoptosis or autophagy. PCD is carried out in a biological process, which usually confers ...

(apoptosis),

cellular senescence Cellular senescence is a phenomenon characterized by the cessation of cell division. In their experiments during the early 1960s, Leonard Hayflick and Paul Moorhead found that normal human fetal fibroblasts in culture reach a maximum of approxim ...

, or

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated diges ...

. In

apoptosis Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes ( morphology) and death. These changes in ...

, the cleavage of DNA is done by Ca²⁺ and Mg²⁺ -dependent

endonucleases Endonucleases are enzymes that cleave the phosphodiester bond within a polynucleotide chain. Some, such as deoxyribonuclease I, cut DNA relatively nonspecifically (without regard to sequence), while many, typically called restriction endonucleases ...

. Image:nuclear changes.jpg, Morphological characteristics of pyknosis and other forms of nuclear destruction. File:Apoptotic neutrophil with nuclear fragmentation.jpg, Microscopy of an apoptotic neutrophil with nuclear fragmentation (H&E stain)

References

Cellular processes Cellular senescence Programmed cell death {{Cell-biology-stub

See also

References