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cellular swelling

Monday 30 January 2006

Cellular swelling is the first manifestation of almost all forms of injury to cells. It is a difficult morphologic change to appreciate with the light microscope; it may be more apparent at the level of the whole organ.

When it affects many cells in an organ, it causes some pallor, increased turgor, and increase in weight of the organ. On microscopic examination, small clear vacuoles may be seen within the cytoplasm; these represent distended and pinched-off segments of the endoplasmic reticulum. This pattern of nonlethal injury is sometimes called hydropic change or vacuolar degeneration. Swelling of cells is reversible.

The ultrastructural changes of reversible cell injury include:
- plasma membrane alterations

  • blebbing
  • blunting
  • distortion of microvilli

- creation of myelin figures
- loosening of intercellular attachments
- mitochondrial changes

  • mitochondrial swelling
  • mitochondrial rarefaction
  • appearance of small phospholipid-rich amorphous densities

- dilation of the endoplasmic reticulum

  • detachment
  • disaggregation of polysomes
    nuclear alterations
  • disaggregation of granular and fibrillar elements

Example

- hepatocyte swelling