Neural Induction and Patterning in the Mouse in the Absence of the Node and Its Derivatives

摘要: Abstract The signals which induce vertebrate neural tissue and pattern it along the anterior–posterior (A-P) axis have been proposed to emanate from Spemann's organizer, in mammals is a structure termed node. However, mouse embryos mutant for HNF3β lack morphological node derivatives yet undergo induction. Gene expression domains occur at their normal A-P axial positions tubes an apparently temporal manner, including most anterior posterior markers. This patterning occurs absence of known organizer genes, inducers chordin noggin. Other potential signaling centers gastrulating appear express constellation putative secreted factors, consistent with possibility that neural-inducing -patterning elsewhere or earlier time. Nevertheless, we find primitive streak, derives, are direct sources signals, as judged by early midbrain marker Engrailed, explant–recombination experiments. Similar experiments showed activity mutants be diffusely distributed. Our results indicate mammalian capable induction plate, but maintenance organizer-like center not necessary either process.