Summary of preimplantation embryonic development. (A) Photomicrographs of human embryos from representative stages of preimplantation development. (B) Table of all the transcriptional arrays performed with pertinent collection parameters. The average Pearson correlations are listed for every experimental group. (C) Hierarchical clustering of gene expression in human, mouse, and bovine embryos during representative stages of PED. This clustering is based on 8479 (human), 7093 (mouse), and 9474 (bovine) informative probe sets. Adjacent stages tend to exhibit similar transcriptional profiles, except for those stages near the time of zygote genome activation. Later PED stages, characterized by expression of genes important for cellular differentiation, segregate into clusters distinct from earlier stages in all three species.
