How does an embryo know its head from its tail?
In the 1990s, a steady-handed scientist combined skills in microsurgery and genetics to overturn our understanding of how embryos develop.
Cells in the early embryo must decide whether to become bone, muscle, or an organ, and something must tell each cell where to go and which part of the body to make.
For 70 years, scientists believed that cells inside the embryo guided this entire process. Then, Rosa Beddington from the National Institute for Medical Research made a surprising discovery: she showed that tissue outside the embryo instructs the head to form. By studying mice, Rosa showed that faulty genes in this tissue could have severe consequences for the developing embryo.
Drawing by scientist Rosa Beddington to illustrate the conservation of developmental pathways between the mouse, frog, fruit fly and fish
The National Institute for Medical Research is now part of the Francis Crick Institute, where Kathy Niakan’s lab is mapping the complex web of factors that control the fate of each cell shortly after a human egg is fertilised.