Thickness profiling of formaldehyde-fixed cells by transmission-through-dye microscopy.

Conventional light microscopy techniques are poorly suited for imaging the vertical cell dimension. This can be accomplished using transmission-through-dye (TTD) imaging, in which cell thickness is directly converted into image intensity in the presence of extracellular dye with strong absorption. We have previously described applications of TTD to living cells using the dye Acid Blue 9 (AB9) to generate contrast.