Microtubules in sand dollar embryo expressing three tandem GFPs fused to the ensconsin microtubule-binding domain (EMTB-3G; Faire et al., 1999). Vegetal view, 28-cell sand dollar embryo show astral microtubules frequently cross spindle midplane before and during anaphase, approach within 1 µm of the equatorial surface before furrowing, and curve inward as the furrow ingresses. Sand dollar embryos were imaged with a laser scanning confocal microscope (Radiance 2000; Bio-Rad Laboratories) mounted on a compound microscope (E800; Nikon) using a 40× 1.3 NA Plan-Fluor oil lens. Room temperature was maintained at 14–17°C, which is tolerated well. Corresponds to Fig 1B and second segment of Video 1 in J Cell Biol. 2009 Dec 14;187(6):831-45.