Figure 2.

(A) The general distribution pattern is illustrated here by camera lucida plotting of labeled cells in chimera 4. Although complicated, the distribution pattern is not haphazard. Three distinguished features of distribution are illustrated in B, C, and D. First (B), labeled cells tend to occupy certain layers in laminated brain regions. For example, labeled cells (red—pseudocolored to highlight the position of cells at low magnification) are restricted to the outermost superficial gray layer in the superior colliculus in chimera 5. Second (C), the deployment of labeled cells in deferent brain regions is distinct. As shown here, labeled cells were distributed evenly along the outer margin of the dentate gyrus (filled triangle) but were scattered discontinuously in the nearby Ammon’s horn (unfilled triangle; chimera 4). Third (D), the same region-specific deployment of labeled cells can be found in other animals, such as the hippocampal region of chimera 1 shown here. (Bar = 100 μm.)