An ex vivo system to study cellular dynamics underlying mouse peri-implantation development

Abstract

Summary Upon implantation, mammalian embryos undergo major morphogenesis and key developmental processes such as body axis specification and gastrulation. However, limited accessibility obscures the study of these crucial processes. Here, we develop an ex vivo Matrigel-collagen-based culture to recapitulate mouse development from E4.5 to E6.0. Our system not only recapitulates embryonic growth, axis initiation, and overall 3D architecture in 49% of the cases, but its compatibility with light-sheet microscopy also enables the study of cellular dynamics through automatic cell segmentation. We find that, upon implantation, release of the increasing tension in the polar trophectoderm is necessary for its constriction and invagination. The resulting extra-embryonic ectoderm plays a key role in growth, morphogenesis, and patterning of the neighboring epiblast, which subsequently gives rise to all embryonic tissues. This 3D ex vivo system thus offers unprecedented access to peri-implantation development for in toto monitoring, measurement, and spatiotemporally controlled perturbation, revealing a mechano-chemical interplay between extra-embryonic and embryonic tissues.

Coordination Between Embryo Growth and Trophoblast Migration Upon Implantation Delineates Mouse Embryogenesis

“…Notably, the postulated tension release at the embryo-substrate interface exactly corresponds to the condition required for pTE cells to constrict apically, invaginate and form ExE -which had been achieved ex vivo only by removing the mTE and releasing tension acting on the pTE (Bedzhov et al, 2014;Ichikawa et al, 2022). Light-sheet microscopy and measurement of the pTE cell aspect ratio showed that pTE cells indeed undergo apical constriction (Figure 4F-G) within the predicted time interval (Figure 4E), indicating that the 3E-uterus recapitulates the embryo-uterus interaction, releasing the TE tension and enabling the development of the whole embryo ex vivo for the first time.…”

“…Cell counts for E4.5-E6.0 in utero embryos were obtained from the previous study (Ichikawa et al, 2022).…”

“…Ex vivo culture of peri-implantation mouse embryos has been developed both in 2D (Hsu, 1972(Hsu, , 1973Morris et al, 2012;Bedzhov et al, 2014) and 3D (Govindasamy et al, 2021;Ichikawa et al, 2022).…”

“…The former generates the extraembryonic ectoderm (ExE) tissue and the latter differentiates into giant trophoblast (GT), while EPI and ExE proliferate and elongate to form an “egg cylinder”. The extraembryonic lineages neighboring the EPI, ExE and visceral endoderm (VE) derived from PrE, play a key role in embryonic growth, patterning and body-axis formation via signaling (Brennan J. et al, 2001; Ichikawa et al, 2022; Rodriguez et al, 2005). In addition to these interactions between embryonic and extra-embryonic tissues post-implantation, the maternal uterine tissues establish a unique context for mammalian development.…”

A New Horizon in Reproductive Research with Pluripotent Stem Cells: Successful In Vitro Gametogenesis in Rodents, Its Application to Large Animals, and Future In Vitro Reconstitution of Reproductive Organs Such as “Uteroid” and “Oviductoid”

“…On the other hand, many groups demonstrated the recapitulation of the implantation-like signal and postimplantation development of mammalian blastocysts upon the gastrulation stage using biocompatible gels and optimized culture methods [ 54 , 55 , 56 , 57 , 58 , 59 ], although the development of the embryos in these studies was limited upon the gastrulation and three-germ-layer segregation, which was far from the hindlimb formation stage (E11 in mice) as reported in the ex utero mouse study [ 52 ]. Thus, in vitro reconstitution of the uterus (“uteroid”, named as PSC-derived uterus-like organoid) from PSCs would make it feasible to achieve omnis ex vivo full-term embryonic development only using stem cells.…”