Gene Coexpression and Evolutionary Conservation Analysis of the Human Preimplantation Embryos

Figure 7

(a) Two models—the “funnel-like” model and the “hourglass” model, revealed by the evolutionary constraint on the whole developmental process of organism. Corresponding stages are labeled on the right side and earlier stages to late stages are in bottom to up sequence. Pharyngula stage (phylotypic stage) is displayed by pink rectangle on the left side. (b) The fluctuation of evolutionary constraints on the stages of human preimplantation embryonic development. In the left side, preimplantation stages are ranked from bottom to up. Maternal transcripts degrade and ZGA are labeled with purple rectangle and yellow rectangle, respectively.