Vertebrate development starts with fertilization. It gradually transforms into a complex three-dimensional geometry. The gastrulation is the earliest event to remodel the pluripotent single cell-layered epithelium into an embryo organized in three distinct germ layers: ectoderm, mesoderm and endoderm. Despite the importance of gastrulation in rearranging the early embryonic tissue, the embryo is far from being complete, and has formed the primordia of the head, heart and gut. Only in a subsequent step of body elongation the embryo will generate most its body (e.g. all vertebrae, the spinal cord and limbs). In amniotes embryos, both gastrulation and body elongation take place sequentially at the primitive streak, a transient midline structure, where cells internalize and trigger the expression of cell type specific genes. However, it is unclear how these processes are related, how they are differentially regulated and even the differences between cell types that they generate remains elusive. My project aims to elucidate the tissue, cellular and molecular dynamics of germ layer formation and body elongation using a quail or a chicken embryo as a model systems, which naturally lends itself to live imaging approaches and experimental manipulations due to its external development. Altogether it clarifies the entire dynamic sequence of events that enable the formation of the entire embryonic axis, from head to tail.
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