Microtubules are dynamic in hyp7 precursors. (A–C) Representative images of GFP::β-tubulin from time-lapse sequences during intercalation and nuclear migration. Anterior is to the left. (A) Microtubules are a meshwork early in intercalation. (B) As cells intercalate, microtubules reorganize into parallel bundles. (C) During nuclear migration, most microtubules are in long bundles that appear dense at cell–cell boundaries. (D) FRAP curves from GFP::β-tubulin embryos. (E) Images of GFP::β-tubulin from a representative FRAP experiment. Bars, 10 µm.