Fig. 6. Morphology of chromosomes during cell division of zebrafish blastomeres at the early blastula stage (2.5 hpf). Electron micrographs showing longitudinal sectioned mitotic chromosomes (A, compare with Fig. 4B) and chromosomes at an early karyomere stage (B, earlier than that shown in Fig. 4C). Numerous flattened vesicles are attached to the surface of mitotic chromosomes (A), and nuclear envelope fragments containing pore complexes are attached to the surface of each chromosome at the early karyomere stage (B). Bars, 0.5 µm.