Lipofuscin is an aging pigment that accumulates in cells. Which of the following best describes lipofuscin?

Lipofuscin is an aging pigment that accumulates in cells. Which of the following best describes lipofuscin?

• A. Melanin
• B. Hemosiderin
• C. Lipofuscin
• D. Bilirubin

Answer: (C)

Lipofuscin is the wear-and-tear pigment that accumulates in aging cells. It consists of lipid-containing residues from lysosomal digestion that build up as cells undergo autophagy over time. This yellow-brown pigment is autofluorescent and tends to appear in long-lived cells like neurons and cardiac myocytes, increasing with age. Among the options, this description fits lipofuscin itself. The other pigments have different origins: melanin is produced by melanocytes for pigmentation, hemosiderin is an iron-containing pigment from breakdown of hemoglobin, and bilirubin is a breakdown product processed by the liver.

Lipofuscin is the wear-and-tear pigment that accumulates in aging cells. It consists of lipid-containing residues from lysosomal digestion that build up as cells undergo autophagy over time. This yellow-brown pigment is autofluorescent and tends to appear in long-lived cells like neurons and cardiac myocytes, increasing with age. Among the options, this description fits lipofuscin itself. The other pigments have different origins: melanin is produced by melanocytes for pigmentation, hemosiderin is an iron-containing pigment from breakdown of hemoglobin, and bilirubin is a breakdown product processed by the liver.