Lipofuscin, the golden yellow pigment is seen in hea muscles in: March 2007

Ans. A: AtrophyThe lipofuscin pigment may impa a brownish discoloration to tissues when present in sufficient amounts (atrophy).Lipofuscin is an insoluble pigment which represents the indigestible residue of autophagic vacuoles within cells formed during aging or atrophy.The following is the manner in which lipofuscin is formed:"During atrophy and aging, degenerating cellular organelles are enclosed in autophagic vacuoles.Subsequently, lysosomes discharge their hydrolytic enzymes into these membrane bounded vacuoles and the cellular organelles are digested by autophagy.However, some of the organelle components may resist digestion or be incompletely digested. (Lipoproteins and other lipids make up most of the indigestible debris and their accumulation reflect the lack of sufficient quantities of lipase in most lysosomes.)When organelles are not digested completely, the debris persists as membrane-bounded residual bodies. Some of these residual bodies may be extruded from the cytoplasm, or may be eventually digested.However, in some instances, the residual bodies persist in cytoplasm of atrophic or aging cells.Lipofuscin occurs in a variety of organs and tissues, but it see specially prominent in the brain neurons, myocardial cells and in the adrenal and thyroid glands.Vitamin E deficiency may accentuate lipofuscin formation.