All of the following are features of reversible cell injury EXCEPT:
A. Detachment of ribosomes from rough endoplasmic reticulum
B. Cellular swelling due to Na+ influx and water accumulation
C. Mitochondrial swelling with cristae disruption
D. Irreversible loss of plasma membrane integrity with leakage of intracellular contents
Explanation
Reversible vs Irreversible Cell Injury: Ultrastructural Features
Key Distinction
Key Point
Reversible cell injury is characterized by structural and functional changes that can be restored to normal if the injurious stimulus is removed. Once plasma membrane integrity is lost with leakage of intracellular contents (particularly enzymes like LDH, AST, CK), the injury becomes irreversible.
Ultrastructural Features of Reversible Injury
Table
Feature
Reversible
Irreversible
Cellular swelling
Present (cytoplasmic edema)
Severe, progresses to lysis
Mitochondrial changes
Swelling, cristae disruption
Swelling with amorphous densities, calcification
Plasma membrane
Intact, blebs form
Loss of integrity, rupture
Ribosomes
Detach from RER
Detach from RER
ER changes
Dilation, ribosome loss
Dilation, fragmentation
Nucleus
Intact, may show pyknosis
Pyknosis → karyorrhexis → karyolysis
Leakage of contents
Minimal
Massive leakage of enzymes/ions
Why Option 2 Is Correct
High-YieldNEET PG
Irreversible loss of plasma membrane integrity with leakage of intracellular contents (LDH, AST, troponin, myoglobin) is the hallmark of irreversible injury, not reversible injury. This represents the "point of no return" — once the cell membrane ruptures, homeostasis cannot be restored and the cell undergoes necrosis.
Why Other Options Are Correct Features of Reversible Injury
1.
Cellular swelling (Option 0): Results from Na+/K+-ATPase dysfunction → Na+ accumulation → osmotic water influx. This is reversible if ATP is restored.
2.
Mitochondrial swelling with cristae disruption (Option 1): Occurs early in reversible injury due to impaired oxidative phosphorylation and Ca²+ overload. Mitochondria can recover if energy supply is restored.
3.
Ribosome detachment (Option 3): Occurs in both reversible and early irreversible injury. Detachment from rough ER leads to polysome disaggregation and reduced protein synthesis — reversible if stimulus is removed.
Clinical Pearl
Clinical Pearl
In acute myocardial infarction, reversible injury occurs within the first 20–30 minutes of ischemia (ultrastructural changes only). After 60–90 minutes, irreversible changes (sarcolemmal rupture, mitochondrial calcification, myofibrillar loss) begin. This is why the "golden window" for reperfusion therapy is critical.
Mnemonic
Mnemonic
CRISP = Changes Reversible In Structural Pathology
