Fig 6.

Sensing of a 3D edge triggers tubulogenesis. (A and B) show two wells of 24-well plates with HPTCs. Multiple tubules with attached myofibroblast aggregates (two of these structures are marked by arrows) are present within these wells (well diameter = 15 mm). The tubules always display a similar distance from the edge, which leads to the generation of ring-like structures consisting of tubules. (C and D) show initial retraction of the monolayer starting at the edge the wells. Uneven illumination is due to optical effects at the edge. The direction where the edge is located is indicated by large arrowheads, and part of the edge is visible in the upper right corner in (C). A part of the monolayer is visible in the lower left corner in (C). All cells of the monolayer moved simultaneously from the edge towards the centre, leaving an almost void surface behind. (D) shows a cell layer that retracted from the edge. Here, coordinated retraction from the opposite side has started, which breaks up the cell layer (marked by small arrowheads) at defined distances from the outer rim. Scale bars: (A, B) 3 mm and (C, D) 500 μm.