Keeping Options Open

Within a few days of fertilisation, the cells of an embryo can take either of two paths; form the embryo itself, or be in the group that becomes the placenta and yolk sac. As a cell journeys further down a particular path, its options become more limited. Usually, it’s particularly difficult to cross between paths, but the early embryo has a group of ‘backup’ cells that for only a small window could join either path and compensate for any changes. We know very little about these intermediate cells, but now researchers have found a way to grow them in the lab. These intermediate cells assemble into ‘artificial blastocysts’, spheres called blastoids (top row enlarging over 4 days, and ‘sliced’ through, bottom row) providing a new way to study in detail this mysterious stage of how embryos' options are kept open for as long as possible.

This study was in collaboration with the MRC London Institute of Medical Sciences' Developmental Epigenomics group

Written by Sophie Arthur

Sophie Arthur

former Science Communications Officer MRC LMS

Formerly a stem cell biologist, Sophie has since moved into science communication working at the MRC LMS. She also writes an award winning science and education blog Soph talks science.

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• Image adapted from work by Anusha Sathyanarayanan and colleagues
• Embryonic Self-Organization Research Group, Max Planck Institute for Molecular Biomedicine, Münster, Germany
• Image originally published with a Creative Commons Attribution 4.0 International (CC BY-NC 4.0)
• Published in Science Advances, November 2022