Live-imaging of the opossum embryo development: Establishing a new powerful model organism for developmental biology.
Zebrafish and chicken embryo can easily be cultured in vitro from zygote to birth, and new microscopy techniques give access to organs and limbs formation in the context of the whole developing embryo. But no mammal has been born in vitro, starting from a zygote, up to now and imaging a process of the developing embryo from the beginning to the end remain a challenge. To address this problem, wouldn’t another model than the mouse be more suitable for mammalian developmental biology?
The grey-short tailed opossum (Monodelphis domestica) is a small marsupial, of a size comparable to a rat. Its embryos implant in the uterus after 10 days of development spent floating in the reproductive tracts. By that time, the embryo is reaching the end of the somatogenesis stage and the heart is already beating. Implantation itself is superficial, especially compared to the mouse, and last for around three days, before the birth of a “not-so-finished new-born” called a joey.
We achieved for the first time microinjection of mRNA in the opossum zygote and 4-cell embryo, followed by live-imaging on a confocal microscope. We tried culture of the different stages to reveal which processes can be accessed in vitro, and identify the problems to overcome to use the opossum to address all the different questions of developmental biology, starting from the first question: the establishment of the first lineages in the mammalian embryo, in the context of an embryo without inside-outside cue, as the marsupial blastocyst is unilaminar.
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Laboratory for chromosome segregation BDR RIKEN
Domain 2 - UMR 3215 / U934 - Genetics and Developmental Biology