Fig. 8: Calcium regulates the apical emergence of distinct basally localized progenitors.

A Schematic depicting the stages of apical emergence for MCCs, ISCs, and SSCs. B Representative images of the skin epithelium of a stage 33 embryo. The different cell types of tissue are highlighted. C Table and representative images for depicting how F-actin, Ac-tub, and PNA-signals were used for the identification of the different cell types. D Schematic for the experimental protocol used to assess the role of intracellular Ca²⁺ transients during ISC apical emergence. E Representative images of a control and 2APB treated stage 26 embryos. Arrows: MCCs. Asterisks: ISCs. F Quantification of apically emerged ISCs per field of view. Two-sided unpaired student’s t test; ****p  <  0.0001; mean ± SEM. n = 18 regions from 9 embryos per condition. G Quantification of ISCs apical surface area. Two-sided unpaired student’s t test; ****p  <  0.0001; mean ± SEM. n = 159 cells from 5 control embryos and 135 cells from 8 2APB treated embryos. H Schematic for the experimental protocol used to assess the role of intracellular Ca²⁺ transients during SSC apical emergence. I Representative images of a control and 2APB treated embryos. Arrows: MCCs. White Asterisk: ISCs. Black Asterisks: SSCs. J Quantification of apically emerged SSCs per field of view. Two-sided unpaired student’s t test; ****p  <  0.0001; mean ± SEM. n = 10 regions from 5 embryos per condition. Scale bars: 20 μm. Source data are provided as a Source data file. Xenopus embryo illustrations, ©Natalya Zahn (2022).