This year's lecture will focus on the most recent developments in the production and culture of pseudo-embryos in ex-uterocultures (embryoids, blastoids, gastruloids, integrated embryos), with particular emphasis on those produced from human embryonic stem cells. What are the scientific reasons and justifications for such research programs ? Can these pseudo-embryos develop over time, implant and give rise to viable fetuses ? And are they really copies of embryos, or just models that only partially represent certain stages of our development, ersatz embryos that provide access to mechanisms that are otherwise impossible to analyze in the human embryo for ethical and legal reasons ?
The last few years have seen a surge in this kind of research, an avalanche of work that is remarkable both for its scientific value and its potential impact, both on our way of thinking about the biological status of the embryo, and on our future possibilities for instrumentalizing these biological objects for medico-social reasons. It is therefore time to take stock of these various " embryo fabrications " and to ask ourselves what their present and future usefulness might be. Priority will be given to methodology and recent results, with the aim of providing precise information on what is possible today in this new field of synthetic embryology. We will also discuss some of the ethical and social issues raised by this work, which will be addressed in greater depth at the annual colloquium also devoted to this subject, to be held on June 7, 2024 at the Collège de France.