Fig. 8. Perpendicular divisions generate molecularly distinct daughter cells. (A-C) Perpendicular divisions in isolated blastomeres generate one daughter cell with localised aPKC and one daughter cell without. Blastomeres were stained with aPKC (red) and ß1 integrin (green). A transmitted light image is shown below the fluorescent image. (A) An isolated blastomere. (B) An isolated blastomere during a perpendicular division. (C) Superficial (top) and deep (bottom) daughters generated after an isolated blastomere completes a perpendicular division. (D,E) The divisions generate differences that lead to later differences in gene expression. (D) An isolated 64-cell stage blastomere was left to divide, separated into a deep and a superficial cell, and cultured until control embryos reach stage 10. (E) Gene expression of the cultured blastomeres was analysed by quantitative real time RT-PCR. The y-axis shows expression in arbitrary units, with 100 being the same level as a stage 10 animal cap. Odc and XSox3 are equally expressed, while ESR6e is preferentially expressed in outer cell derived clones. The mean of three independent experiments is presented.