Water bubbles are seen microscopically on an H&E slide. This could probably be prevented by:

• A. Making sure the dehydration step is complete
• B. Extending the water rinse
• C. Lowering the staining time
• D. Using hot water

Answer: (A)

Water bubbles seen under a microscope on an H&E slide usually come from moisture that wasn’t removed from the tissue before mounting. The dehydration step is designed to replace water in the tissue with alcohol, so that subsequent clearing and the mounting medium can seal the section without trapping water. If dehydration is incomplete, residual water can remain in cells or between tissue and the slide, forming tiny pockets that appear as bubbles under the coverslip.

Hence, ensuring the dehydration step is complete eliminates the water that would otherwise cause these bubbles, making it the best preventive measure. Extending the water rinse wouldn’t reliably remove internal moisture once the tissue has absorbed water from fixation; lowering the staining time or using hot water wouldn’t address the underlying issue and could introduce other artifacts.