Figure 9. Conserved proliferation and neurogenesis processes, but divergent signaling mechanisms in the forebrain in lampreys and gnathostomes.

A and B summarize the main findings of this study. In A, the neurogenesis pattern schematized is highly comparable to what has been found in jawed vertebrates. By contrast, in B, four major signaling systems which control the growth, the patterning, and the morphogenesis of the forebrain are depicted, and the type of difference when compared to jawed vertebrates is indicated. C provides a more detailed comparison of the Wnt signaling pathways in embryonic lampreys (present data) and in zebrafish (compiled from ZFIN and [56]). It should be noted that the absences of expression we observed for signaling systems in telencephalon await for evidences from functional and/or complete genomic data that these apparent lacks are not compensated by other family members.