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Fig. 6. Confocal image of live embryo at the beginning of the second cleavage,
continuously bathed in FM1-43 and cytochalasin B. Figure shown is a flat
projection of a stack of images captured through 300 µm of specimen depth.
Fluorescing FM1-43 accumulates in the new membrane domain of the first
cleavage plane (broad vertical stripe), but not in the original membrane
domains (asterisk). Localized bright-staining puncta along the new/old
membrane boundaries correspond to collections of long microvilli, and do not
represent sites of endocytosis (data not shown). Membrane newly inserted along
the second cleavage furrow (surrounding arrow) is momentarily less
well-labeled than that previously inserted along the first furrow.