Which of the following is the EARLIEST ultrastructural change detectable in a cell undergoing reversible hypoxic injury?
- A Rupture of plasma membrane
- B Swelling of endoplasmic reticulum and mitochondria with loss of mitochondrial cristae ✓
- C Amorphous densities in the mitochondrial matrix
- D Fragmentation of nuclear chromatin
Correct answer: B. Swelling of endoplasmic reticulum and mitochondria with loss of mitochondrial cristae
Explanation
The earliest consequence of hypoxia is decreased oxidative phosphorylation with ATP depletion. Within minutes this fails the Na-K ATPase, causing cellular and organelle swelling with loss of microvilli and blebs, plus dissociation of ribosomes from rough ER. Amorphous matrix densities indicate irreversible mitochondrial injury, nuclear fragmentation defines apoptosis or late necrosis, and plasma membrane rupture marks irreversible injury, all occurring later than reversible swelling changes.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.