Feeling a Pulse

Stem cells need some direction during gastrulation – the process that sees them grow into different tissues inside an embryo. Proteins called morphogens send guiding signals deep into each stem cell’s nucleus, where lifelong decisions are made. In this cluster of human embryonic stem cells – a sort of artificial early embryo – scientists watch for responses to morphogen molecules. While some early changes happen around the perimeter (highlighted in red), a signal called Nodal spreads inwards (green), leading some cells (blue) to begin changing, or differentiating, into the mesoderm, where muscles form in real embryos. Watching these living ‘models’ reveals that Nodal responds to rhythmic waves of chemical 'messages' – a sort of developmental pulse that may help to understand, or even assist, decisions made at the earliest stages of life.

Written by John Ankers

John Ankers

Writer

A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Image from work by Idse Heemskerk and colleagues
• Department of Biosciences, Rice University, Houston, TX, USA
• Image originally published under a Creative Commons Licence (BY 4.0)
• Published in eLife, March 2019