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Cellular Swelling and Fatty Change: Understanding Reversible Cell Injury

Learn about cellular swelling and fatty change, two types of reversible cell injury, including their mechanisms, morphologies, and effects on organs such as the liver and heart.

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Cellular Swelling and Fatty Change: Understanding Reversible Cell Injury

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  1. SECTION 2 CELL INJURY

  2. Cellular Swelling Fatty Change Hyaline Change Amyloid Change Mucoid Change Pathologic Pigmentation Pathologic Calcification • Reversible Degeneration • Irreversible Cell Death

  3. Reversible Cell Injury Degeneration Intracellular &/or extracellular abnormal accumulation: • Excess amounts of various normal substances (water,lipids,proteins,pigments) • Abnormal substances (exogenous, endogenous)

  4. (1) Cellular Swelling (hydropic degeneration) Intracellular accumulation • Sodium • Water

  5. (2) Cellular Swelling Morphology the organs NE: • Cloudy swelling • Increase in the weight the cells LM: • Large • Small & fine granules in the cytoplasm Ballooning change Swelling • Endoplasmic reticulum • Mitochondria EM：

  6. ATP Water & sodium within the cells Injurious agents Mechanism Mitochondria damage Cellular swelling

  7. Fatty Change (1) Steatosis Intracellular abnormal accumulation: • Triglycerides Often occurred in the liver and the heart

  8. Fatty Change (2) Morphology • Large • Yellow • Soft • Greasy NE: Fat vacuoles LM: • Round, clear vacuoles • Orange-red color by staining with Sudan Ⅲ or Oil Red O (Frozen tissue sections!) Liposomes EM： • Membrane-bound inclusions

  9. (1) Fatty Change of the Liver NE • Mild fatty change: Not affect the gross appearance • With progressive accumulation: • Large • Yellow • Soft • Greasy Fatty Liver: Severe & diffuse fatty change

  10. (2) Fatty Change of the Liver LM Fat vacuoles Small , in the cytoplasm around the nucleus Displacing the nucleus to the cell periphery Fatty cysts

  11. (3) Fatty Change of the Liver Mechanism

  12. Fatty Change of the Myocardium NE • Mild fatty change: Not affect the gross appearance • With progressive accumulation: Tigered effect Apparent bands of yellowed myocardium alternating with bands of dark,red-brown,uninvolved myocardium

  13. Hyaline Change (1) A descriptive morphologic term A homogeneous, translucent, pink appearance in HE staining Intracellular or extracellularabnormal accumulation: • Proteins

  14. Hyaline Change (2) • Hyaline change in arteriolosclerosis • e.g. Hypertension, Diabetes • Hyaline change in connective tissues e.g. Old scars • Hyaline change within the cytoplasm e.g. Nephrotic syndrome, Russell bodies, Mallory body

  15. Amyloidosis Extracellular abnormal accumulation: • Amyloid

  16. Physicochemical characteristics of amyloid • +Iodine--- a brown color--- +H2SO4 --- blue • Staining: Congo red--- red, HE--- homogeneous pink • EM: nonbranching fibrils 7.5-10 nm wide • X-ray: a pleated –sheet structure (rendering protein very resistant to enzymatic degradation, contributing to its accumulation in tissues)

  17. Mucoid Change Extracellular abnormal accumulation: • Mucopolysaccharide (Glycosaminoglycans, Hyaluronic Acid)

  18. Pathologic Pigmentation Intracellular & extracellular abnormal accumulation: Colored substances • Exogenous • Endogenous

  19. Pathologic Pigmentation • Exogenous • Endogenous • Carbon • Hemosiderin • Lipofuscin • Melanin

  20. Pathologic Calcification (1) • Except for the bones and teeth • Pathologic conditions Intracellular & extracellular abnormal accumulation: • Calcium salts

  21. Pathologic Calcification (2) • Dystrophic Calcification In areas of necrosis No calcium metabolic derangements • Metastatic calcification In normal tissues Some calcium metabolic derangements

  22. Irreversible Cell Injury Cell Death 1. Necrosis A sequence of morphologic changes that follow cell death in living tissue 2. Apoptosis A distinctive and important mode of cell death regulated by genes

  23. (1) Necrosis Two essentially concurrent processes to produce the morphologic changes : 1.Enzymatic digestion of the cell 2. Denaturation of proteins Autolysis Heterolysis

  24. (2) Necrosis • Basic pathologic changes • Types of necrosis • Sequences of necrosis

  25. (3) Necrosis Basic Pathologic Changes Pyknosis • Nuclear changes Karyorrhexis Karyolysis • Cytoplasm Increased eosinophilia

  26. (4) Necrosis Types of Necrosis • Coagulative necrosis • Liquefactive necrosis • Caseous necrosis • Fat necrosis • Gangrene • Fibrinoid necrosis

  27. Coagulative Necrosis • A mass of coagulated, pink-staining, homogeneous cytoplasm • Preservation of the basic structure outline of the coagulated cell or tissue for several days • In solid organs (kidney, heart, spleen )

  28. Liquefactive Necrosis • Liquefaction of necrotic cells • Condition: Presence of more abundant proteolytic enzymes • Most often in suppurative inflammation & in the brain

  29. Caseous Necrosis • A distinctive form of coagulative necrosis • Cheese-like • An amorphous coarsely granular eosinophilic debris • Most often in foci of TB

  30. Fat Necrosis • A special type of liquefactive necrosis • Focal areas of fat destruction • Calcium soaps • Enzymatic fat necrosis(acute pancreatitis) • Nonenzymatic fat necrosis (following direct trauma to adipose tissue & extracellular liberation of fat)

  31. Gangrene • Extensive tissue necrosis • Secondary bacterial infection • Dry gangrene • Wet gangrene • Gas gangrene

  32. Fibrinoid Necrosis • A type of connective tissue necrosis • Loss of normal structure • A homogeneous,bright pink-staining necrotic material that resembles fibrin microscopically

  33. (5) Necrosis Consequences of Necrosis • Autolysis & inflammation • Dissolution & absorption • Sloughing Ulcer, Cavity, Sinus, Fistula • Organization & encapsulation • Calcification

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