Stable astral microtubules form without Rho activity. Medial single-section confocal images of D. excentricus zygotes. (A–D) Cells were treated with 20 μM ncdz for 5 min (12°C), then fixed and stained to reveal ncdz-resistant microtubules. (E–H) Cells were injected at least 15 min before NEB with C3, which induced an extended interphase. C3-injected cells were monitored under bright field until they resumed mitosis, transferred at the desired stage into 20 μM ncdz for 5 min (12°C), then fixed and stained identically to the noninjected cells. Shown are anaphase (A and B, and E and F), telophase (C and G), and early interphase (D and H). Arrowheads indicate condensed interpolar array, which is absent from same-stage C3-injected cells. Loss of dynamic astral microtubules frequently permits the interpolar array to slip sideways during ingression (as in D). Bar, 25 μm.