Overview. + Stress. Normal cell. Adapted Cell. - Stress. +Stress. Injury. - Stress. Reversibly injured cell. Apoptosis. Irreversibly Injured cell. Dead cell. Necrosis. LO. Define necrosis Enlist types of necrosis
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
(1) Definition: Localized death of cell or tissue occurring in the living body.
(2) Cell death is recognized by:
②Changes in the nucleus.
Normal Pyknosis Karyorrhexis Karyolysis
（参照武忠弼 病理学规划教材第一版 人民卫生出版社1979，修改)
③Changes in cytoplasm staining
- loss of RNA (basophilia)
- denatured cytoplasmic protein
– large, whorled phospholipid mass (phospholipid precipitate)
HISTOLOGIC FEATURES OF COAGULATIVE NECROSIS
Reversible cell injury with cytoplasmic & organelle swelling, blebbing & ribosome detachment
Irreversible cell injury with rupture of membrane & organelles, & nuclear pyknosis
① Coagulative necrosis:
Gross features: The necrosis area is swollen, firm and pale.
LM: cell detail is lost, but architecture preserved. The dead cells retain their outline but only indistinctly.
This type of necrosis is frequently caused by lack of blood supply and is exemplified well in infarcts of solid organs, e. g. heart, spleen, kidney.
This is an example of coagulative necrosis. This is the typical pattern
with ischemia and infarction (loss of blood supply and resultant tissue
anoxia). Here, there is a wedge-shaped pale area of coagulative necrosis
(infarction) in the renal cortex of the kidney.
Coagulative necrosis of the left ventricular wall
（From ROBBINS BASIC PATHOLOGY，2003）
Ischemic necrosis of the myocardium
A, Normal myocardium.
B, Myocardium with coagulation necrosis
Special types of coagulative necrosis
Definition: necrosis of big tissue with superadded putrefaction, black, fou-smelling appearance.
Necrosis of big tissue putrefactive black, green
Or organ or limb organisms infection appearance
(black or green due to breakdown of haemoglobin)
Types of gangrene:
a. Dry gangrene:
Conditions: only occurs on the skin surface following arterial obstruction. It is particularly liable to affect the limbs, especially the toes.
Types of gangrene:
b. Wet gangrene:
Conditions: Both arterial and venous obstruction; wet in environment;
Character: wet swollen, foul-smelling, black or green.
Commonly in small intestine, appendix, lung, and uterus, also in limbs.
Types of gangrene:
c. Gas gangrene:
Conditions: deep contaminated wounds in which there is considerable muscle damaged by gas formation bacteria.
Character: swollen obviously, gas bubbles formation. The infection rapidly spreads and there is associated severe toxaemia.
Only occasionally in civilian practice but is a serious complication of war wounds.
Soft and liquid grossly. Enzymes digest the cell and convert it to a formless proteinaceous mass. Ultimately, discharge of the contents forms a cystic space. i. e. central nervous system after ischemic injury; abscesses.
:microscopic – granulomatous inflammation
A tuberculous lung with a large area of caseous necrosis
Tuberculous granuloma showing an area of central necrosis, epithelioid cells, multiple Langhans-type giant cells, and lymphocytes.
Grossly: Opaque and chalky
LM: outline of necrotic fat cells filled with amorphous basophilic material (calcium soaps).
i. e. Digestion of peritoneal fat by pancreatic enzymes in pancreatic inflammation.
Foci of fat necrosis with saponification in the mesentery
Fibrinoid change in blood vessel
(4) Consequences of necrosis
① Acute or chronic inflammation
② Immunological reactions to sub cellular components released by dead tissue or self-antigens altered by denaturation.
③ lysis and absorption
④ Isolation and discharge: ulceration and cavity formation