Introduction Mesoderm is an embryonic germ layer which gives rise to a variety of tissues, including skeleton, muscle, kidney, as well as the blood- and immune system. While the formation of the skelletal system depends on dorsal mesoderm, ventral mesoderm is giving rise to connective tissue, blood and immune cells. Regulation of early dorso-ventral territories will therefore determine the bodyplan of the embryo. Mesoderm is induced by peptide growth factors very early in development and is the driving force of gastrulation. Gastrulation is a morphogenetic process where mesodermal cells migrate inside the embryo such that the three germ layers, ectoderm, mesoderm and endoderm, attain their final position in the embryo.
Gastrulation starts in the so called Spemann organizer.
This tissue which consists of primordial mesoderm, was identified by transplantation experiments in 1926 by Spemann and Mangold. The transplanted organizer is able to induce a twinned embryo in a receiving host. In the department, the molecular basis of this phenomenon is studied, as it may reveal the basic mechanisms of axis formation in vertebrates. In particular, the mechanisms of mesodermal cell differentiation and migration are investigated. A working model for early mesoderm formation is shown in Figure 1. 2.