1. Necrosis and apoptosis

2. Objectives Define necrosis and apoptosis
List the different types of necrosis, examples of each and its features
List the different conditions associated with apoptosis, its morphology and its mechanism
Know the difference between apoptosis and necrosis

3. Objectives Define necrosis and apoptosis
List the different types of necrosis, examples of each and its features
List the different conditions associated with apoptosis, its morphology and its mechanism
Know the difference between apoptosis and necrosis

4. Cell Death
Death of cells occurs in two ways:
Necrosis--(irreversible injury) changes produced by enzymatic digestion of dead cellular elements
Apoptosis--vital process that helps eliminate unwanted cells--an internally programmed series of events effected by dedicated gene products

5. Objectives Define necrosis and apoptosis
List the different types of necrosis, examples of each and its features
List the different conditions associated with apoptosis, its morphology and its mechanism
Know the difference between apoptosis and necrosis

6. Morphology of necrosis :
Cellular swelling or rupture
Denaturation  and coagulation of cytoplasmic proteins
Breakdown of cell organelles
Breakdown of nuclear DNA

7. Patterns of Necrosis In Tissues or Organs
As a result of cell death the tissues or organs display one of these six macroscopic changes:
Coagulative necrosis
Liquifactive necrosis
Caseous necrosis
Fat necrosis
Gangrenous necrosis
Fibrinoid necrosis

8. Patterns of Necrosis In Tissues or Organs
Coagulative necrosis:
the outline of the dead cells are maintained and the tissue is somewhat firm.
Example: myocardial infarction 
Liquefactive necrosis:
the dead cells undergo disintegration and affected tissue is liquefied.
Example: cerebral infarction.

9. Patterns of Necrosis In Tissues or Organs 3. Caseous necrosis:
a form of coagulative necrosis (cheese-like). Example: tuberculosis lesions.
4. Fat necrosis:
enzymatic digestion of fat.
Example: necrosis of fat by pancreatic enzymes.
5. Gangrenous necrosis:
Necrosis (secondary to ischemia) usually with superimposed infection.
Example: necrosis of distal limbs, usually foot and toes in diabetes.
6. Fibrinoid necrosis: typically seen in vasculitis and glomerular autoimmune diseases

10. Changes in the cytoplasm and the nucleus
Coagulative Necrosis
Changes in the cytoplasm and the nucleus  
Karyorrhexis
Karyolysis 
Pyknosis

11. Necrosis of the liver induced by herpesvirus.
Herpesvirus invades liver cell nuclei producing nuclear ('ground glass') mildly basophilic inclusions.

12. Acute renal tubular necrosis (ischemia) :
increased eosinophilia and pyknosis in necrotic cells
Normal
Necrotic

13. Ischemic neuronal injury:acidophilic cytoplasm & nuclear pyknosis

14. … a mess - so many cells have died - the tissue is not recognizable
… a mess - so many cells have died - the tissue is not recognizable. Nuclei have become pyknotic (shrunken and dark), undergone karorrhexis (fragmentation) and karyolysis(dissolution)
Necrotic myocardium

15. Removal of the dead tissue leaves behind a scar
Coagulative necrosis
Kidney: ischemia and infarction
(loss of blood supply and resultant
tissue anoxia).
Removal of the dead tissue leaves behind a scar

16. Infarcts (vascular distribution) are wedge-shaped
Coagulative necrosis: is due to loss of blood supply
Infarcts (vascular distribution) are wedge-shaped
with a base on the organ capsule.
Spleen

17. Depending on circumstances:
necrotic tissue may be walled off by scar tissue,
totally converted to scar tissue,
get destroyed (producing a cavity or cyst),
get infected (producing an abscess or "wet gangrene"),
or calcify.
If the supporting tissue framework does not die, and the dead cells are of a type capable of regeneration, you may have complete healing.
Remember: True coagulation necrosis involves groups of cells, and is almost always accompanied, by acute inflammation (infiltrate)