FIGURE 4.

In vitro models of the segmentation clock. (a) Differentiation of PSCs in monolayer culture leads to synchronously oscillating PSM cells. No wave patterns are observed, as indicated by the vertical orientation of lines in the kymograph. (b) Performing the initial steps of PSM differentiation in 3D aggregates and subsequently allowing these aggregates to spread on culture dishes leads to wave‐like patterns of segmentation clock oscillations. Traveling waves can be seen as lines with a slanted slope in the kymograph. (c) Gastruloids can recapitulate traveling waves of the segmentation clock coupled with morphological somite formation when embedded in low‐percentage Matrigel. Traveling waves can be seen as lines with a slanted slope in the kymograph. Light brown: progenitor domain, dark teal: posterior PSM; light teal: anterior PSM; purple: somites