Fig. 1. Approach and experimental set-up.

a, b Schematic of the approach. a Left: Drawing of a curved epithelial tissue. The tissue may be overlaid by a second epithelium to be discarded by the imaging process. Right: We first estimate the surface of interest (red mesh) using a small fractional pre-scan (green dots). b After surface estimation, we either scan a thin shell (blue) around the surface of interest (left side) or we propagate the scanning process along the cell outlines (right side). The zoom in the inset shows the propagation front in red while the previously sample voxels are in green. c Experimental set-up