pbl embryos show defects in central spindle maintenance, furrow ingression, and vesicle transport. Genotypes are indicated on the right. All images show live embryos. Fluorescent α-tubulin was injected at cellularization. (A) Central spindle and furrow MT formation in WT. Bracket, central spindle; arrows, furrow MTs. (B) Mitotic cells in pbl⁵ mutants show midzone MTs but lack furrow MTs and a stable central spindle. (C) pbl⁵ phenotype ranges from cells that lack a central spindle to cells with a strong central spindle. Central spindle severity (left) correlates with defects in furrow invagination (middle) and actin puncta mislocalization (right). n is shown in parenthesis. For full videos, see Videos 8 and 9. Bars, 5 μm.