Necrosis of cells is due to -
Ans. is 'd i.e., Enzymatic digestion o Cell injury is reversible upto a ceain point, but if the stimulus persists, irreversible injury and ultimate cell death occur. o There are two principal patterns of cell death : ? a Necrosis q Apoptosis Necrosis o Necrosis refers to a spectrum of morphological changes that follow cell death in living tissue. o Remember this fact Cell death is not due to necrosis rather necrosis (i.e., morphological changes) occurs after cell death cells placed immediately in fixative are dead but not necrotic. Necrosis only represents the morphological changes that occur after cell death. o These morphological changes (necrosis) is the result of 2 concurrent processes : ? 1. Enzymatic digestion of the cell q Enzymes used in the process are derived from two sources :? (a) From the lysosomes of the dead cells themselves (Autolysis) (b) From the lysosomes of the immigrant leukocytes (Heterolysis) 2. Denaturation of intracellular proteins o These processes require hours to develop, So immediatly after cell death there are no detectable necrotic changes. o Necrosis usually effects a group of contigous cells (in contrast to apoptosis that involves death of a single cells), but it can effect single cell also. o In necrosis, there is diruption of membrane integrity --3 Intracellular contents leak out and elicit inflammation --> Inflammatory changes in the surrounding tissue (By contrast, in apoptosis there is no inflammatory reaction in the tissue). Morphological changes o As necrosis follows irreversible injury, the morphological changes are same that have been described in irreversible injury. These are ? 1.Membrane damage 2.Large flocculent amorphous densities in mitochondria. 3.Intracytoplasmic myelin figures 4.Decreased basophilia and increased eosinophilia due to decreased RNP. 5.Nuclear changes : Karyolysis --> Basophilia of chromatin Pyknosis --> Nuclear shrinkage Karyorrhexis --> Fragmentation of Pyknotic nucleus.
Ca' efflux in cell
Fat deposition in cells
Water imbibition in cells
Enzymatic digestion