Figure 5.

Sequence of photos from SDS-treated, equalized embryo. Compare to Figure 4. (a) Vegetal pole at 16-cell stage, as identified by 4 blastomeres at this pole, 8 blastomeres at the opposite pole, and 4 blastomeres in the middle tier. (b) The 5^th cleavage at the vegetal pole. (c) The 32-cell stage showing nuclei of the vegetal blastomeres. The cells identified by cleavage orientation as being of small micromere (SMi) lineage are pictured. (d) Synchronous 6^th cleavage at the vegetal pole, in contrast to control embryos. One cleavage furrow is slightly eccentric (arrow). (e) The 64-cell stage, a stage not achieved by control embryos. Note the single smaller blastomere (arrow). (f) Nuclear membrane breakdown for the 7^th cleavage. The smaller blastomere is the last to undergo nuclear membrane breakdown (arrow). (g) The 128-cell stage. Another unequal cleavage produced a small blastomere (arrow). (h) This small blastomere (arrow) is the last to divide at 8^th cleavage. (i) The vegetal pole at the 256-cell stage of this equalized embryo. Compare to Figure 4i.