- Lipofuscin
- Wear and tear pigment accumulating in secondary lisosomes -> converted into compact residual bodies
- Due to old age, past or recent cachexia or starvation
- Mostly stored in skeletal muscle of old high producing dairy cattle
- Masseters and diaphragm mainly involved
- No clinical importance
- Histologically:
- Rounded yellow to brown granules at both poles of nucleus of the skeletal myofiber
- Melanin
- As part of congenital melanosis of calves in fascial sheaths and epimysium
- Grossly - black foci
- Myoglobin
- After extensive muscle necrosis - rhabdomyolysis
- Leaks to adjacent tissue after sudden injury
- May also be present after some types of intramuscular injections e.g. iron dextran or tetracycline