In lead poisoning, the characteristic basophilic stippling of red blood cells results from aggregation of which organelle?
- A Mitochondria
- B Ribosomes ✓
- C Golgi apparatus
- D Lysosomes
Correct answer: B. Ribosomes
Explanation
Lead inhibits 5'-nucleotidase, the enzyme responsible for degrading ribosomal RNA during red cell maturation. As a result, aggregated ribosomes persist in the cytoplasm and stain as basophilic stippling on a Romanowsky-stained blood film. This finding is not pathognomonic (also seen in thalassaemia, megaloblastic anaemia, pyrimidine 5'-nucleotidase deficiency) but is highly characteristic of lead toxicity when combined with clinical features. Lead also inhibits ALA dehydratase and ferrochelatase, causing porphyrin accumulation.
Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.
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