Morphologic changes in necrotic cell

MORPHOLOGIC CHANGES  IN NECROTIC CELL

• Definition- Necrosis refers to spectrum of  morphologic changes that follow cell death in living tissue, largely resulting from the progressive degradative action of enzymes on lethally injured cell

• The morphologic appearance of necrosis is the result of denaturation of intracellular proteins & enzymatic digestion of the cell

• The enzymes are derived from either lysosomes of the dead cells themselves (Autolysis)or from the lysosomes of the immigrant leukocytes (heterolysis )

Morphology of necrotic cell

• Microscopic appearance

  Cytoplasmic changes

  • Increased eosinophilia – Due to denatured proteins and loss of cytoplasmic RNA

  • Glassy homogenous appearance – loss of glycogen particles

  • Moth eaten appearance of cytoplasm – enzymatic digestion of cytoplasmic organelles

  • Whorled phospholipid masses derived from damaged cell membranes – myelin figures

  • Calcifications – fatty acids derived from phospholipid masses

• Electron microscopic findings

  Necrotic cells are characterised by

  • Discontinuities in plasma and organellar membrane

  • Swollen mitochondria with large amorphous densities

  • Intracytoplasmic myelin figures

  • Aggregates of fluffy material representing denatured proteins

• Nuclear changes

  • Due to non-specific break down of DNA , 3 patterns are identified

    • Karyolysis – fading of basophilia of chromatin due to enzymatic degradation of DNA by endonucleases

    • Pyknosis – nuclear shrinkage & increased basophilia

    • Karyorrhexis – pyknotic nucleus undergoes fragmentation

Reference

1. Vinay kumar, Abul K.Abbas, Jon C. Aster. Cellular responses to stress and Toxic insults: Adaptations, injury and Death. In: Robbins and Cotran Pathologic basis of disease 9th edition Vol 1.31-68.