![]() ![]() Characterizing the zebrafish organizer: microsurgical analysis at the early-shield stage. Axis-inducing activities and cell fates of the zebrafish organizer. Saùde, L., Wooley, K., Martin, P., Driever, W. Transplantation experiments on developing teleosts (Fundulus and Perca). Über Induktion von Embryoalanlagen durch Implantation artfremder Organisatoren. ![]() In contrast to induction of the vertebrate head, known to result from the triple inhibition of BMP, Nodal and Wnt 5, here we show that induction of the tail results from the triple stimulation of BMP, Nodal and Wnt8 signalling pathways. Moreover, stimulation of naive cells by a combination of BMP, Nodal and Wnt8 mimics the tail-organizing activity of the ventral margin and induces surrounding tissues to become tail. Loss-of-function experiments reveal that bone morphogenetic protein (BMP), Nodal and Wnt8 signalling pathways are required for tail development. Here we reveal, by isochronic and heterochronic transplantation, the existence of a tail organizer deriving from the ventral margin of the zebrafish embryo, which is independent of the dorsal Spemann organizer. However, whereas the graft can induce ectopic head and trunk, endogenous and ectopic axes fuse in the posterior part of the body 3, 4, raising the question of whether a distinct organizer region is necessary for tail development. The equivalent of this organizer region has been identified in different vertebrates including teleosts 2. ![]() Based on grafting experiments, Mangold and Spemann showed the dorsal blastopore lip of an amphibian gastrula to be able to induce a secondary body axis 1. ![]()
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