Unequal Inheritance

This is an early mouse embryo showing, left to right, one cell progressing through division. The protein building machinery (cyan) and RNAs (pink) are being unevenly distributed with much of the former ending up in the outer daughter cell and much of the latter in the inner one. As in all mammalian embryos, those outer cells will soon form the placenta and so must quickly get on with the job of building it – hence the retention of protein building or translation machinery. The inner cells, on the other hand, retain a lot of RNA but don’t readily translate it, instead maintaining the pluripotency that will allow them to eventually become every single cell type of the growing foetus. Gaining insights into how cellular components are distributed to daughters and how this influences cell fate decisions widens our understanding of development and informs the creation and improvement of regenerative therapies.

Written by Ruth Williams

Ruth Williams

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Ruth is a freelance science journalist based in the US. She's a regular correspondent for The Scientist, and her work has appeared in The Lancet, Nature, Scientific American Mind, BBC Focus and elsewhere. Twitter @rooph

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• Image from work by Azelle Hawdon and colleagues
• Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria, Australia
• Image copyright held by the original authors
• Published in Nature Communications, May 2023