Karyorrhexis

Karyorrhexis (from Greek κάρυον karyon, "kernel, seed, nucleus," and ῥῆξις rhexis, "bursting") is the destructive fragmentation of the cell nucleus that occurs in a dying cell. It is characterized by the breakdown of the nuclear envelope and the dispersal of condensed chromatin into the cytoplasm. The process is usually preceded by pyknosis (irreversible chromatin condensation) and followed by karyolysis (enzymatic dissolution of chromatin). It may occur during programmed cell death (apoptosis), cellular senescence, or necrosis.

In apoptosis, karyorrhexis is mediated by Ca2+- and Mg2+-dependent endonucleases, ensuring that nuclear fragments are packaged into apoptotic bodies and removed by phagocytosis. In necrosis, by contrast, nuclear fragmentation occurs in a less orderly fashion, leaving behind cellular debris that can contribute to tissue damage and inflammation.

  • Morphological features of pyknosis and other forms of nuclear destruction
  • Microscopy of an apoptotic neutrophil with nuclear fragmentation (H&E stain)
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