CONSEQUENCES OF CELL INJURY
When studying CELL INJURY, it is well to remember that eventually all cells die. It has been said that life is a fatal disease - eventually we all die. Thus in cell injury, we are really concerned with PREMATURE dysfunction and cell death.
What are the basic mechanisms of cell injury?
These systems are all interrelated - damage may begin with disruption of
  • the ENERGY SUPPLY or
  • the CELL MEMBRANE.

There are two outcomes - recovery or death. Purists might add another - incomplete recovery (the cell does not return to complete normality).

We thus can classify injury as REVERSIBLE or IRREVERSIBLE.

What are the outcomes for cell injury?
REVERSIBLE vs IRREVERSIBLE
The hepatocytes shown in this visual are injured. Can you spot the reversible changes and the irreversible changes?
The 3 nuclear changes in irreversable cell injury are -
  • shrinkage = PYKNOSIS
  • breaking up of nucleus = KARYORRHEXIS
  • loss of nucleus = KARYOLYSIS
Note the liver in this cow. In the pictures below are a cross section through the liver and a histological section...

Look at all views and then come up with a tentative diagnosis?

Cross section through bovine liver
Histological section of liver
Examine this microscopic image. Is the primary change in the cytoplasm or the nuclei?
This is a histological section of epidermal skin. Is this change reversible or irreversible?
This is a section of skin from a rabbit with myxomatosis - a disease that may be fatal to the rabbit. Is this change reversible or irreversible?
This is the liver from an aborted foal. Therefore we know the foal is dead. The foal died as a result of cellular injury. Describe the lesion. Click here for a description.
This is a histologic image of the liver from the same foal. What is your lesion diagnosis?
Okay, now let's look at another kind of nuclear lesion...
Several cells in this liver have "shrunken" or PYKNOTIC nuclei. The chromatin has condensed into a small blue "dot". This indicates irreversible injury has occurred in these cells. Do you see the agent?
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