Proliferating cells are found throughout the 96 h gastruloid.

A: Immunostained sections of four gastruloids that were fixed at 96 h. Left: immunostaining of Brachyury/T, Sox2 and the proliferation marker Ki-67. Right: The same sections, but only the immunostaining of Ki-67 is shown. Cell nuclei were stained with DAPI. Scale bars: 100 μm. B: Distribution of the relative positions of proliferating cells (Ki-67-positive) along the long axis (left) or short axis (right) of the respective gastruloid. (EPS)