Pyknosis, karyorrhexis, and karyolysis are sequential nuclear changes seen in necrosis. The enzyme primarily responsible for karyolysis is:

• A Caspase-3
• B Lysosomal DNase (acid DNase) released from ruptured lysosomes ✓
• C DNase I activated by calcium
• D Cathepsin D

Explanation

In necrosis, lysosomal membrane rupture releases acid DNase and other hydrolytic enzymes that digest nuclear DNA, causing karyolysis (nuclear dissolution). Caspase-3 activates caspase-activated DNase (CAD) in apoptosis, producing the organized internucleosomal fragmentation seen on gel electrophoresis. Calcium-activated DNase I is more relevant to early necrotic changes; cathepsin D is a lysosomal protease but not primarily responsible for nuclear dissolution.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.