Question

Lipofuscin granules present in nerve cells are actually
A. Primary lysosomes
B. Digestive vacuoles
C. Residual bodies
D. Newly digested lipids

Answer 1

Hint: Lipofuscin is also called wear and tear pigment because its amount keeps increasing as time passes. It is seen in the kidney, nerve cells, retina, heart muscles and ganglion cells. It is yellowish-brown in color and has lipids containing residues. It mainly occurs due to alteration of the macromolecules by oxygen derived free radicals.

Complete answer:
> Option A: Primary lysosomes: - They are mainly membrane bound and are formed from the Golgi apparatus. They can breakdown or digest the materials that are entering from an extracellular environment.

> Option B: Digestive vacuoles: - They are also called food vacuoles which are found in parasites and are responsible for causing malaria. They are formed by the combination of lysosome and phagosome. Digestive enzymes are present in these which digests the nutrients properly.

> Option C: Residual bodies: - These contain indigestible materials. Lipofuscin contains the residues of lipid in lysosomal digestion. So this option is apt for the above question.

> Option D: Newly digested lipids: - Digestion of lipids starts in the stomach with the help of lingual and gastric lipases. They are digested and then get absorbed in the small intestine.

Hence, the correct answer is option (C).

Note: The major age related changes are due to the deposition of this Lipofuscin in the neuron’s cytoplasm. Formation of this pigment starts from the early developmental processes and advances with age. It is mostly not detected in neurons of the young organisms including humans. Then, with the advancement in age, clumps of these starts to form. However, the staining properties vary with different age groups.