Central spindle and contractile ring are not formed during binucleation. Photomicrographs showing cross-sectional views of cells (A–O) and their schematic diagrams (A’–O’) are arrayed from left to right according to the M phase progression. (A–E) Main cells during cell division stage in early pupa (30–35 hours APF). (F–J) Main cells during binucleation stage in mid-pupa (60–65 hours APF). (K–O) Binucleation-stage main cells in which pebble was overexpressed just before binucleation. Arrowheads in (D, E, I, J, N and O) indicate equatorial planes in late anaphase and telophase during cell division and binucleation. Cells are labeled as indicated at the bottom of (E). Scale bar in (A), 5 μm, is applicable to (A–O).