Micrograph sections of d30 b-CTRL, UL1 and UL4 hCOs immunostained for proliferation markers KI67 and PH3. The dashed lines represent the apical surface of the cavities/ventricles. Quantification of the total number of proliferating Ki67+ cells/area (µm2) of ventricles like structures and of the number of PH3+ cells facing the ventricle/apical surface length (µm). Data shown as Z-scores relative to the mean of b-CTRL. Nuclei (blue) are stained with DAPI. 