Dr. R. Geetha M.D.
Department of Pathology
DEFINITION OF NECROSIS
Spectrum of morphologic changes
that follows cell death in living
CAUSES OF NECROSIS
PATHOGENESIS OF NECROSIS
1.Denaturation of intracellular proteins.
2.Enzymatic digestion of the cell.
Increased eosinophilia of cytoplasm
Glassy homogeneous appearance
Cytoplasm is vacuolated,moth eaten
Calcification of dead cells.
Appearance of myelin figures
Generation of calcium soaps
Fading of basophilia of chromatin
Due to DNAase activity.
Nuclear shrinkage and
Fragmentation of pyknotic nucleus
Preservation of general tissue
of the cells.
Affected tissue is firm
Denaturation of structural proteins
and enzymatic digestion of cells.
Example – Heart, kidney,spleen.
WET GANGRENE DRY GANGRENE
Venous obstruction Arterial obstruction
Moist,swollen,dark Dry, shrunken, black
No clear line of Presence of line of
Bacteria present No bacteria
Prognosis poor Prognosis better
Wet gangrene caused by gram
positive anaerobic bacteria
Seen in muscle and in colon