Question: How can I more easily visualize the fiducial frame during tissue section placement?
Answer: Prior to pre-cooling the Visium Gene Expression slide in the cryostat, trace the fiducial frame(s) on the back of the slide with a permanent marker. Ensure the sticker at the top of the slide is facing down and not readable. After performing the 1 min drying step at 37C and before methanol fixation, remove the ink with a 100% ethanol-soaked laboratory wipe. Ensure the ink is completely removed prior to methanol fixation and avoid touching the active side of the slide when performing the above steps.