Endogenous pigments are characterized as hematogenous and nonhematogenous. Hematogenous pigments originate from blood and nonhematogenous pigments originate from non-blood, fat or fatlike, and non-fatlike substances.
Examples of endogenous hematogenous pigments found in the liver are hemosiderin and bilirubin. Examples of endogenous nonhematogenous pigments found in the liver are lipofuscin (fatlike) and copper (non-fatlike). Fetal liver tissue will always demonstrate endogenous nonhematogenous copper pigment.
The table provides more detail on examples of endogenous pigments:
- Hemosiderin is ferric (+3 charge) iron and can be identified in organs such as the liver, spleen, and bone marrow.
- Often demonstrated in the condition known as hemosiderosis, caused by an increase in iron intake.
- Hemosiderosis may be attributed to transfusion, excess dietary iron consumption, or the breakdown of red blood cells.
- One of the most common endogenous pigments found in human tissues.
- A yellowish-brown pigment found in increased amounts as cells age.
- Commonly known as "age pigment."
- Nerve, cardiac, and liver cells commonly demonstrate lipofuscin.
- A bile pigment that is excreted by the hepatocytes of the liver.
- When bilirubin is not excreted by hepatocytes, jaundice or yellowing of the skin can occur.
- Jaundice is characteristic of several liver diseases.
- A commonly known liver disease that causes jaundice in infants is neonatal hyperbilirubinemia, caused by hepatocytes that have underdeveloped smooth endoplasmic reticulum (SER).
- A unique characteristic of fetal liver tissue is that it will ALWAYS demonstrate the presence of copper.
- For this reason, fetal liver tissue acts as a good copper tissue control.