Accumulation of F-actin in the contractile ring is incomplete during MK endomitosis. MKs were stained for F-actin (phalloidin-TRITC, red) or tubulin (green) and TOTO (blue). (A) F-actin accumulation around the midzone at the site of furrow ingression in dipolar mitotic/endomitotic MKs (i,ii). Incomplete F-actin accumulation (arrows) at the site of furrow ingression in multipolar endomitotic MKs (iii,iv). (B) In multipolar endomitosis, accumulation of F-actin was seen at only some parts of midzone where a local ingression is seen (arrows). (C,D) Rho inhibition by TatC3 prevents F-actin accumulation (C) and RhoA localization (D) in the midzone and spindle elongation.