ISL1 and cyst: (K, L) Quantification of GATA3 and ISL1/2 fluorescent intensities in 24 (blue, n=115 cells) and 48 hr (red, n=76 cells) BMP4 treatment samples (K), as well as of nuclear aspect ratios of d4 hPSC-cyst (black, n=63 cells), and 24 (blue, n=45 cells) and 48 hr (red, n=52) BMP4-treated cysts (harvested at d4), (L).