Figure 3

Distribution of pericentromeres and centromeres at different stages of mouse preimplantation development. Single confocal sections (A-H) of each preimplantation stage with pericentromeric (major satellite, red), centromeric (minor satellite, green), and DNA (grey) labeling are presented here, as well as the corresponding 3D reconstructions (A'-H'). (A, A') Example of an embryo at the early 2-cell stage. Pericentromeres and centromeres are essentially located at the periphery of NPBs, but some NPBs remain devoid of any signal. (B, B') In embryos at the late 2-cell stage, pericentromeric signals are now forming more spherical patches mostly associated to NPBs. The following images show embryos cultured up to the 4-cell (early C, C’ versus late D, D'), 8-cell (early E, E' versus late F, F’), 16-cell (G, G') and blastocyst (H, H’) stage. Pericentromeric and centromeric heterochromatin now forms chromocenters of heterogenous sizes and shapes. Note that at the blastocyst stage we randomly analyzed the trophectoderm cells and the inner cell mass. Bars = 5 μm.