On the Clock

Insects like beetles have a body made up of different segments. Although you may not realise, human bodies – and those of other mammals – are also segmented, although in a less obvious way. During development in the womb, our spinal column is built from repeated segments known as somites, which are laid down in strict order from top to bottom. Using mouse embryos as a model for humans, researchers have been exploring how this clockwork somite pattern is created. The image on the left is a normal mouse embryo around 8 days after fertilisation. The activity levels of a gene called Hes7 highlighted in different colours from blue (low) through green and yellow (medium) to red (high), with the resulting stripes determining where the somites will grow. The embryo on the right has an alteration in a gene called Fgf4, disrupting the developmental clock and causing serious defects within the body.

Written by Kat Arney

Kat Arney

Writer

Dr Kat Arney is an award-winning science writer, broadcaster and public speaker, and is the founder and Creative Director of First Create The Media.

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• Image from work by Matthew J Anderson and colleagues
• Genetics of Vertebrate Development Section, Cancer and Developmental Biology Laboratory, National Cancer Institute, National Institutes of Health, Frederick, MD,USA
• Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in eLife, November 2020