Which of the following is an indicator of poor fixation of electron microscopy specimens?

• A. Disrupted mitochondrial membranes
• B. Intact mitochondrial membranes
• C. Well-preserved membranes
• D. Normal cell morphology

Answer: (A)

In electron microscopy, the fixation step must stabilize membranes and cellular structures so they don’t change or collapse during processing. Mitochondrial membranes are especially sensitive to inadequate fixation; if the fixative didn’t cross-link and preserve the lipids and proteins effectively, the membranes can become disrupted or ruptured. Therefore, seeing disrupted mitochondrial membranes is a clear indicator that fixation was poor. In contrast, intact and well-preserved membranes, along with normal cell morphology, point to good fixation and proper specimen processing.