Figure 5.

Air bubbles trapped in gel/oil A-D) (Left), 6×6mm mosaics at subsequent depths show a dark shadow (yellow dashed oval) created by a bubble in the gel (immersion fluid) traveling horizontally across the mosaics and ultimately spreading over a larger area as the objective lens moves within the gel. E, F) (Right), 6×6mm mosaics at subsequent depths plus 1×1mm insets show the varying morphologies of air bubbles trapped in oil (index fluid) and how they change with increasing imaging depth. The red insets show irregular round to indented bright structures superficially, which become more fringed on the deeper mosaic. The green inset shows similarly shaped bubbles also filling surface irregularities or adnexal ostia, but rather than being bright, these thinner bubbles show a bright periphery and an internal fringe pattern with similar brightness to the surrounding tissue. The bubble (yellow arrow) in the yellow insets, fills a round indent, probably an eccrine ostium, and is bright white, mimicking a milial cyst, but the fringe pattern on the deeper mosaic, which could be confused with a melanocytic nest, confirms that this is a bubble. The orange inset shows thin bubbles filling the wrinkles. On the deeper mosaic, these appear similar to the bubbles in the green insets. Of note, all of these images also display some degree of the mosaic grid pattern.