Which of the following is the earliest ultrastructural change identifiable by electron microscopy in reversible cell injury?
- A Plasma membrane blebbing
- B Clumping of nuclear chromatin
- C Swelling of endoplasmic reticulum and mitochondria ✓
- D Myelin figures (whorled membrane structures)
Correct answer: C. Swelling of endoplasmic reticulum and mitochondria
Explanation
The earliest EM change in reversible cell injury is swelling of the endoplasmic reticulum and mitochondria (hydropic change at the organelle level) due to loss of ion pumps and water influx following ATP depletion. Plasma membrane blebbing and myelin figure formation also occur early but follow organellar swelling; chromatin clumping (pyknosis) is an irreversible/apoptotic change. Ultrastructurally, ribosomal detachment from the ER (polysome disaggregation) occurs concurrently.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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