Fig. 4. The influence of the animal-vegetal axis on the generation of different blastocyst patterns. (A-C) Classification of mouse embryos according to sequence and orientation of second cleavage divisions. (A) To measure the angle () between the division planes of the 2-cell blastomeres (white lines), 3D representations were rotated to assess the angle (illustrated by the eye). (B) Scheme illustrating the measurement of the distance of cells to the polar body (PB, see Materials and methods). (C) Box-plot showing relationship between the four embryo classes and . Beneath is shown the average angles for each class; n, sample size. (D) The frequency of the different blastocyst patterns in each of the four embryo classes.