RhoA^Δ/Δ primitive erythroid cells are often multinuclear. (A) PI staining of E12.5 primitive circulating erythroid cells reveals a significant number of 4N, >4N, as well as <2N cells in the RhoA^Δ/Δ population compared with the almost exclusively 2N cells of the WT population. The graphs are representative of 3 biological repeats. Insets: representative imaging flow cytometry pictures of brightfield and Syto-16–stained WT and RhoA^Δ/Δ primitive erythroid cells within the 2N (top) and 4N gate (bottom). (B) Graphic representation as mean ± SEM from the data of 3 experiments (3 different biological repeats) of PI staining of E12.5 primitive erythroid cells. *P < .005 of RhoA^Δ/Δ vs WT. (C) Imaging flow cytometry reveals that tetraploid (4N) and >4N RhoA^Δ/Δ primitive erythroid cells do not appear to be undergoing mitosis. Cells were stained with the nuclear stain Syto16. Micronuclei or nuclear fragments (arrows) can be observed in the >4N population.