Progressive change in MTOCs and the time required for division. (A) Progressive change in diameter of MTOCs shortly before NEBD in the embryos at consecutive developmental stages. (B) Whisker box plot of the number of MTOCs per cell at one-cell, two-cell, eight-cell, E3.5, and E4.5 stages, shortly before NEBD. The lines near the middle of the boxes represent the median (50th percentile). The bottom and top of the boxes are the 25th and 75th percentile, respectively. The end of the bottom whisker is the 5th percentile, and the end of the top whisker is the 95 percentile. (C) Duration of cell division (from NEBD to the beginning of anaphase) at consecutive stages of preimplantation development. Note that from the eight-cell stage on, the duration of cell division (∼20 min or less) becomes only twice as long as the time interval of recording (every 10 min); thus, the data cannot be as precise (indicated by a broken line) as those for the earlier stages. In A and C, the vertical bars indicate the range of values.