Abstract
Some notions of comparative embryology, ES cells and iPS cells as basic material for making pseudo-embryos. Long-term embryo culture ex-utero ; production of human blastoids, efficacy, in vitro implantation tests , comparison with mice.
This second lesson begins with a description of some of the differences between the early development of mouse and human embryos, followed by a reminder of the global function of gastrulation in the spatial organization of embryonic sheets. Next, a new protocol is described which allows pre-gastrulation murine embryos to be grown in culture to an advanced fetal stage, enabling in vitromonitoring of morphogenesis - an approach that was impossible just a few years ago.
The lesson continues with a review of the origin and potential of embryonic stem cells ESCs and reprogrammed cells iPSCs, which are the basis for the production of pseudo-embryos. Then, the first type of pseudo-embryo, blastoids, is described and the protocols used in rodents and humans are compared. Human stem cells are capable of self-organization and of producing such blastocyst models with high frequency. Using an in vitroimplantation system based on uterine endometrial organoids, it even appears that these human blastoids can implant in a uterine mucosa following hormonal stimulation.
