Figure 1. De novo emergence of centrosomes and centrioles in murine embryos. (A) Confocal Z-projections of GFP::CETN2-labeled and γ-tubulin immunolabeled embryos. Quantification of the proportion of nuclei with an associated GFP::CETN2 centriole pair (10–23 embryos/stage examined) or γ-tubulin focus (6–12/stage) is to the right. Note that the 2-cell embryo fluorescence pattern was identical to the 4-cells. (B) A zoomed image of a GFP::CETN2 blastocyst. Note pairs of GFP::CETN2-labeled centrioles associated with each nucleus. (C) Colocalization of γ-tubulin with GFP::CETN2-labeled centrioles. (D) Comparison of the proportion of Oct4-positive and Oct4-negative cells possessing centrioles in early cavitating blastocysts (n = 18). Note that although there is a greater proportion of centriole-containing cells in the trophoectoderm (arrowhead) compared with inner cell mass (arrow), the majority of cells possess centrioles in both lineages. Scale 20 µm.