Lamin B opening with H2 release in mouse erythropoiesis. (A) E13.5 TER119 negative mouse fetal liver erythroblasts were purified and cultured in vitro in erythropoietin containing medium. Immunofluorescence stains for lamin B, H2A and DNA (DAPI) from erythroblasts cultured on different days were performed. Arrows indicate lamin B openings. Scale bar: 5mm. (B) Same as A except the cells were from fresh total fetal liver cells (left) and bone marrow erythroblasts. Scale bar: 5mm.