Pyknosis

Pyknosis, or karyopyknosis, is the irreversible condensation of chromatin in the nucleus of a cell undergoing necrosis^[1] or apoptosis.^[2] It is followed by karyorrhexis, or fragmentation of the nucleus. Pyknosis (from Ancient Greek πυκνός meaning "thick, closed or condensed") is also observed in the maturation of erythrocytes (a red blood cell) and the neutrophil (a type of white blood cell). The maturing metarubricyte (a stage in RBC maturation) will condense its nucleus before expelling it to become a reticulocyte. The maturing neutrophil will condense its nucleus into several connected lobes that stay in the cell until the end of its cell life.

Micrograph of an infarct in the biliary tract, with pyknotic nuclei (arrows) (400x).

Pyknotic nuclei are often found in the zona reticularis of the adrenal gland. They are also found in the keratinocytes of the outermost layer in parakeratinised epithelium.

References

^ Kumar V, Abbas A, Nelson F, Mitchell R (2007). Robbins Basic Pathology (8th ed.). pp. 6, 9–10 (table 1-1).
^ Kroemer G, Galluzzi L, Vandenabeele P, Abrams J, Alnemri ES, Baehrecke EH, et al. (January 2009). "Classification of cell death: recommendations of the Nomenclature Committee on Cell Death 2009". Cell Death and Differentiation. 16 (1): 3–11. doi:10.1038/cdd.2008.150. PMC 2744427. PMID 18846107.

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[1] Kumar V, Abbas A, Nelson F, Mitchell R (2007). Robbins Basic Pathology (8th ed.). pp. 6, 9–10 (table 1-1).

[zamzami-2] Kroemer G, Galluzzi L, Vandenabeele P, Abrams J, Alnemri ES, Baehrecke EH, et al. (January 2009). "Classification of cell death: recommendations of the Nomenclature Committee on Cell Death 2009". Cell Death and Differentiation. 16 (1): 3–11. doi:10.1038/cdd.2008.150. PMC 2744427. PMID 18846107.

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v t e Pathology
Principles of pathology	Disease Infection Neoplasia Cause Pathogenesis Hemodynamics Ischemia Inflammation Cell damage Wound healing Cellular adaptation Atrophy Hypertrophy Hyperplasia Dysplasia Metaplasia Squamous Glandular Cell death Necrosis Coagulative necrosis Liquefactive necrosis Gangrenous necrosis Caseous necrosis Fat necrosis Fibrinoid necrosis Myocytolysis Programmed cell death Apoptosis Pyknosis Karyorrhexis Karyolysis Accumulations pigment Hemosiderin Lipochrome/Lipofuscin Melanin Steatosis
Anatomical pathology	Surgical pathology Cytopathology Autopsy Molecular pathology Forensic pathology Oral and maxillofacial pathology Gross processing Histopathology Immunohistochemistry Electron microscopy Immunofluorescence Fluorescence in situ hybridization
Clinical pathology	Clinical chemistry Hematopathology Transfusion medicine Medical microbiology Diagnostic immunology Immunopathology Enzyme assay Mass spectrometry Chromatography Flow cytometry Blood bank Microbiological culture Serology

See also

References