Figure 4.

Bilaterally corresponding structures are typically both populated by ES cell descendants. (A) Although only a small number of labeled cells (pseudocolored to highlight the position of cells at low magnification) was found in this section, the cells were allocated symmetrically in the diencephalon (chimera 4). (B) The medial habenular nucleus (HMb) was not a preferentially incorporated structure, but, when labeled cells were located on one side, they were symmetrically localized on the opposite side of the habenular nucleus (chimera 9). (C) Nevertheless, a unilateral allocation of labeled cells was observed occasionally (chimera 8). (D) One possible mechanism to generate such bilaterally symmetric allocations is that cells of the same ancestry tend to incorporate into bilaterally corresponding structures. The sizes of bilaterally sibling clones, as indicated in the figure, are not necessarily expanded to the same extent. (Bar = 100 μm.)