Astral MTs contribute to midbody assembly in the absence of a central spindle. (A) Representative time-lapse images of GFP::TBB-2β-tubulin-expressing (green, top; inverted grayscale, middle) and mCherry::H2B-expressing (magenta) embryos undergoing midbody assembly. White arrows indicate bundled astral MTs at the furrow. Time relative to midbody assembly. Bottom: Time-lapse pseudokymographs of MTs during midbody assembly. Maximum projection of three Z-sections is shown. See Video 8. Dashed orange box indicates area selected for pseudokymograph; white and vertical black scale bars, 10 µm; horizontal black scale bar, 15 s. (B) Schematic depicting model for midbody assembly in the presence (top) or absence (bottom) of HCP-1/2– or SPD-1–dependent central spindle assembly.
