Branching patterns in tissue may be simpler than we thought

Wellcome researchers have discovered a set of simple rules which may explain how complex branching patterns in tissues such as the mammary glands develop. 

Light micrograph of normal female breast tissue showing aggregations of glandular lobules.

Credit: Astrid Michler / Science Photo Library

Light micrograph of mammary gland tissue. Researchers discovered that complex branched structures in tissue may be governed by simple rules.

The discovery could offer insights into the development of mammary and pancreatic cancer, where the early stages of the disease are characterised by irregular branching structures.

How the research was done 

Branching patterns occur throughout nature – in trees, ferns and coral, for example – but also at a much finer scale, where they are essential to ensuring that organisms can exchange gases and fluids with the environment efficiently by maximising the surface area available.

Researchers compared the growth of ductal tips in the mammary gland with their proximity to maturing ducts in order to derive the simple rules which determine whether a particular branch duct (a single growing branch) will divide again or stop growing.

What the research shows

The team, led by Professor Ben Simons and Dr Edouard Hannezo from the Gurdon Institute, found that ductal tips continue to branch and grow, expanding into empty space, until they meet a mature duct, at which point they stop.

This results in very little overlap of branches and the space being perfectly filled with statistical regularity. Ductal structures appear to both divide and terminate with almost equal probability.

Dr Sheny Chen from Wellcome’s Cellular and Developmental Sciences team said:

“This elegant study helps us understand the decisions our cells make during development. It’s fascinating that simple rules can govern the generation of highly complex patterns and that these rules can apply to different branched structures.”

The researchers think that this branching process in the mammary glands could potentially reflect a widespread self-organising principle of branching morphogenesis, the biological process that causes organisms to develop their shape.

The research was funded by Wellcome with additional core support from Cancer Research UK and the Medical Research Council.

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