Necrosis&apapoptosis

necrosis and apotosis for undergraduate medical students

1. Necrosis and Apoptosis
Dr.P.Rajaguru M.D.(Path)
VMCH&RI, Madurai

2. Objectives
Necrosis
Definition
Causes
Types
Pathogenesis
Morphological aspects
Apoptosis
Definition
Causes
Pathogenesis
Morphological aspects
Differences between necrosis and apoptosis
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4. Necrosis

5. Definition
Pathologically induced cell death with complete destruction.
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6. Causes of necrosis
Infective
Ischemia and hypoxia
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Chemical/Toxin mediated

7. Types of necrosis
Coagulative necrosis
Architecture preserved
Loss of both proteins and enzymes
No proteolysis
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8. Gangrenous necrosis
coagulative-Ischemia
liquefactive-bact infection
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9. Liquefactive necrosis
Accumulation of leucocytes
Release of enzymes
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10. Types of necrosis
Caseous necrosis
Fat necrosis
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11. Morphological changes in necrosis
Reversible injury
Plasma membrane-Blebings
Mitochondria-Swelling and amorphous densities
Endoplasmic reticulum-Dilation, detachment of ribosomes and
myelin figures
Nucleus-start of disintegration
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12. Morphological changes in necrosis
Irreversible injury
Two M’s of irreversibility- Membrane damage & Mitochondrial
damage
Plasma membrane-Discontinuities
Cellular contents-Enzymatic digestion with leak
Nuclear changes-Pyknosis-karyorrhexis-karyolysis
Associated inflammation
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13. Morphological changes in necrosis
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14. Increased eosinophilia-loss of cytoplasmic RNA (which binds
the blue dye, hematoxylin)
Glassy homogeneous appearance-loss of glycogen particles
Cytoplasm-vacuolated and appears moth-eaten
whorled phospholipid masses called myelin figures that are
derived from damaged cell membranes.
Phospholipid precipitates
•phagocytosed by other cells or further degraded into fatty
acids- Calcification of such fatty acid residues results in the
generation of calcium soaps.
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15. Karyolysis- basophilia of the chromatin fade - loss of DNA
because of enzymatic degradation by endonucleases.
Pyknosis, characterized by nuclear shrinkage and increased
basophilia-Chromatin condenses into a solid, shrunken
basophilic mass.
Karyorrhexis, the pyknotic nucleus undergoes fragmentation.
With the passage of time (a day or two), the nucleus in the
necrotic cell totally disappears.
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16. Morphological changes in necrosis
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Normal Reversible injury Irreversible injury

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22. Frame of a skyscraper
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23. Apoptosis

24. Definition
Cell suicide
Physiological or pathological
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25. Causes of apoptosis
Physiological-Programmed cell death
Embryogenesis and developmental involution
Hormone withdrawal
Ovarian atresia-menopause
Immature cells-Bone marrow and thymus
WBC-End of inflammatory response
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26. Causes of Apoptosis
Pathologic causes of apoptosis
DNA damage-Cytotoxic drugs, radiation and hypoxia
Accumulation of misfolded proteins
Infections: mainly viral by inducing Tcell response
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27. Morphological changes in apoptosis
Cell shrinkage
Nuclear condensation
Cytoplasmic blebs-Apoptotic bodies
Phagocytosis
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28. Pathogenesis
caspase is based on two properties
“c” refers to a cysteine protease (i.e., an enzyme with cysteine in its
active site)
“aspase” refers to the unique ability of these enzymes to cleave
after aspartic acid residues
More than 10 members
Two groups—initiator and executioner
Initiator - caspase-8 and caspase-9
Executioners-caspase-3 and caspase-6
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29. Apoptotic proteins
Antiapoptotic-Bcl2 and Bcl-x
Proapoptotic – bad, bak, bid and bim
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34. Dysregulated apoptosis
1.Excessive apoptosis
2.Neurodegenerative disease, stroke and MI
Reduced apoptosis
1.Cancer
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35. Differences between
Necrosis and Apoptosis

36. Rotten apple
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37. Dried apple
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38. Soaked grains
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39. Dried grains
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40. Differences
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41. Take home message
Necrosis-Pathological
Associated with inflammation
Apoptosis-Physiological or pathological
Associated with phagocytosis
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43. Autophagy
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44. Thank You