Extended Data Fig. 1: Neural crest development and vibrating probe setup and calibration.
From: Stretch-induced endogenous electric fields drive directed collective cell migration in vivo
a, Scheme showing the transition of Xenopus laevis embryos from stage 17.5 to stage 23. We refer to these stages as pre- or early migratory stage and migratory, respectively. Streams containing groups of neural crest cells (or clusters) are observed at migratory stages as a sign of directed collective cell migration (dCCM). b, Overview of the vibrating probe setup. c, Zoom-in of the dashed red rectangle shown in (b) showing the measuring chamber with an embryo. M, middle; L, lateral; D, dorsal; V, ventral. d, Upper panel is a zoom-in of the yellow rectangle shown in (d), displaying a vibrating probe in static mode. Scale bar, 50 µm. d, Bottom panel shows the probe in vibrating mode as observed while located in the neural fold position (pos). Neural crest (cyan). Scale bar, 200 µm. e–g, Calibration and validation with an artificial source. e, Example results of vibrating probe calibration with an artificial source at the indicated values (details in Supplementary Note 1). Inset in the top left corner shows a glass microelectrode (point source) and vibrating probe. Scale bar, 150 µm. f,g, Validation results. Reference is recorded when the probe is > 1 mm away from the artificial source and measurements are taken at the indicated distance. g, Current density as a function of the distance to the artificial source using observed in (f) and theoretical data calculated using Equation 1 (Supplementary Note 1). Inset in (g) shows the results of fitting both observed and theoretical results to a linear regression. Note the exponential drop of current density with distance indicating a successful calibration. Two-tailed Pearson’s r2, ****p < 0.0001. h, In vivo probe validation using the blastopore of a Xenopus laevis embryos as a natural source of outward currents and the ventral ectoderm as a point of inward currents (or ‘sink’).
