INTRACELLULAR ACCUMULATIONS, PIGMENTS AND TISSUE DEPOSITS

WHAT IS A DEPOSIT? WHAT IS A PIGMENT? Your text defines deposits and pigments. What is your definition?

TATTOO IS BOTH! (DEPOSIT & PIGMENT)

A deposit is a substance (usually abnormal) which accumulates (is DEPOSITED) inside cells or in the interstitium. If these DEPOSITS are colored - they are also PIGMENTS.

The basis of a tattoo is that the ink (DEPOSIT) will remain in a certain body location and is colored (PIGMENTED) so it is visible.

Tattoos are used in thoroughbred horses to ascertain identity at races.

This is another example of a deposit (india ink) that is pigmented. The ink was injected in this rat to identify regional lymphatics. Where would the ink be deposited after migration through the lymphatics?
One of the functions of macrophages is to be the SCAVENGER of deposits and pigments. Think of another substance that would be scavenged.
This dog was injured and hemorrhage resulted. The tissue is "bruised" or has a contusion. Do you remember the pathogenesis for resolving a bruise?

This is the regional lymph node from an animal with a bruise. Once the red blood cells are phagocytosed and lysed, bile pigments and iron are released.

The brown to black cells in this lymph node are macrophages filled with iron. What is another name for these cells?

What are your rule-outs for the deposits in these cells in the lung? Answer »
How would the lung appear grossly with large amounts of hemosiderin deposits?
The lungs appear tan to brown due to the PIGMENT in the hemosiderin. When hemosiderin is present in large amounts, the condition is called hemosiderosis.

Did you note the cause of the hemosiderosis in this dog?

The lesion seen on this spleen is an example of the reaction that may occur as a result of deposits. What is the reaction?
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