Formation and function of the mouse organizer

After Spemann and Mangold"s discovery of a gastrula organizer in the salamander, the question of the existence of an organizer in other vertebrate gastrula was raised. Because of it size and implantation in the uterus, technical difficulties have hindered experiments to study in detail the mammalian embryo. Recently much light has been shed on this topic, leading to the identification of a gastrula organizer and an anterior signalling center. The gastrula organizer is homologous to the Spemann-Mangold trunk-tail organizer while the anterior signalling center is required together with the organizer to induce a complete secondary axis.
In this chapter, we will address the location and activities of the signalling centers and molecules in the
mammalian, mostly murine, gastrula.