Supervisor: Magdalena Zernicka-Goetz
During implantation, the mouse blastocyst transforms into the post-implantation embryo, an elongated cup-like structure, the egg cylinder. The morphogenetic events responsible for this transition are largely unknown as they take place while the embryo implants into maternal tissues, preventing direct observation and manipulation. Recently a protocol for in-vitro culturing (IVC) mouse blastocysts to post implantation stages was developed in our lab, allowing the live-monitoring of peri-implantation morphogenesis for the first time . During peri-implantation stage the epiblast (EPI), which is the tissue that will give rise to the embryo, is surrounded by two extraembryonic tissues. At the one side the EPI is covered by the trophectoderm-derived Extraembryonic Ectoderm (ExE) and at the other side by the primitive endoderm-derived Visceral Endoderm (VE). Although extraembryonic tissues do not contribute to the embryo-proper, they are indispensable for embryonic development, as they are essential for anteroposterior axis patterning and the formation of the placenta and yolk sac . Despite the detailed characterization of the cellular and molecular mechanisms governing EPI organization during the blastocyst to egg cylinder transition  , the morphogenetic events within the extraembryonic tissues responsible for this transition have not been characterized. Using the IVC system developed in our lab we can now uncover the morphogeneting events within extraembryonic tissue during peri-implantation stages. Intracellular calcium has been identified as a key factor regulating morphogenetic movements in different organisms and tissues . Due to the linkage of Calcium with morphogenetic events one would expect that calcium signaling is involved in the blastocyst to egg cylinder transition, as this is a morphogeneticaly active period. Using transgenic mice expressing a protein coded calcium indicator (GCAMP) and high resolution live imaging we aim to monitor intracellular Calcium dynamics and assess the role of Calcium signalling during extraembryonic tissues morphogenesis.
1. Bedzhov I, Zernicka-Goetz M (2014) Self-organizing properties of mouse pluripotent cells initiate morphogenesis upon implantation. Cell 156: 1032-1044.
2. Richardson L, Torres-Padilla ME, Zernicka-Goetz M (2006) Regionalised signalling within the extraembryonic ectoderm regulates anterior visceral endoderm positioning in the mouse embryo. Mechanisms of development 123: 288-296.
3. Markova O, Lenne PF (2012) Calcium signaling in developing embryos: focus on the regulation of cell shape changes and collective movements. Seminars in cell & developmental biology 23: 298-307.