Figure 7. Collage of clusters.

Cluster formation started to take place in the co-cultures right after gain of confluency and thereafter throughout 8 weeks. A–F) Co-cultures invariably gave rise to clusters of approximately 200–700 µm in diameter. G–I) Occasionally we also observed bigger clusters that were partly detached from the underlying co-culture and held back by a stalk of cells. Scale bar 1 mm.