LF left right organiser

Like all vertebrates, our anatomy is notably asymmetrical, with certain organs on the left and others on the right. This is determined during development by a group of cells called the left-right organiser (LRO) – a structure that only exists transiently in the early embryo. The LRO initiates left-right asymmetry as the embryo develops by controlling directional fluid flow with cilia (whisker-like projections from cells), which induces asymmetric gene activity. Here, researchers investigate how the LRO forms through live-cell imaging in the early hours of developing zebrafish. Starting as a collection of cells, rounds of division shape a fleeting rosette-like structure after which a fluid-filled space (lumen) forms (image shows how normal lumen formation (left in amber) is affected and halted by increasing amounts of growth factor inhibitor middle and right)). The team found that to ensure this series of structural outcomes, events reliant on specific growth factors control the cell divisions and their timing. Understanding how the LRO begins could reveal its hitherto overlooked roles in developmental disorders.

Written by Lux Fatimathas

Lux Fatimathas

Writer

Having pursued science through a career in research, communications and publishing, she is currently a writer and editor for a healthcare marketing agency and also juggles freelance science writing.

• Image from work by Yan Wu and Yiling Lan and colleagues
• Department of Biology, Syracuse University, Syracuse, NY, USA
• Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in Development, May 2025