Pyknosis, or karyopyknosis, is the condensation of chromatin in the nucleus of a cell undergoing programmed cell death (see Naoufal Zamzami and Guido Kroemer: "Apoptosis: Condensed matter in cell death", Nature Vol. 401 p. 127, 9 September. 1999 ^*).

It is followed by Karyorrhexis, or fragmentation of the nucleus.

Pyknosis occurs due to the fragmentation of DNA during apoptosis.

See also

• Apoptosis, especially the section on the morphology of apoptotic cells.
• Karyorrhexis

• Pyknosis
• Necrosis