Fig. 2. Furrow microtubule bundles directly underlie the growing domain of the new membrane. (A) Furrow ceases ingression in an embryo treated with 0.1 µM latrunculin B. New membrane deposition continues, however, producing broad white stripe. (B) Same embryo, fixed and stained with antitubulin antibody. Montage is series of confocal micrographs running along cleavage furrow from animal pole to horizon. The curvature of the embryo is not apparent in montage because individual frames are single projections of image stacks, each representing several tens of microns of specimen depth. Bar, 50 µm.