Molecular Dissection of Hox Gene Induction and Maintenance in the Hindbrain

mechanisms other than those implied by these three “Preformation is represented by DNA, not by . . . a tiny models can at least refine anteroposterior pattern. For adult in every sperm . . .” example, the prechordal mesendoderm emits signals —Antonio Garcı́a-Bellido (1998) that can anteriorize the hindbrain (Dale et al., 1997; Foley “The key to understanding how genomic regulatory et al., 1997; Pera and Kessel, 1997), and interactions networks . . . work lies in experimental analysis of between adjacent regions within the neural tube can cis-regulatory systems at all levels of the regulatory regulate the expression of regional markers (e.g., Itasaki network.” et al., 1991; Martı́nez et al., 1991). Despite this richness —Maria Arnone and Eric Davidson (1997) of ideas and experimental efforts, it seems remarkable