BPoD has moved!

BPoD has recently changed our domain name - we can now be found at bpod.org.uk

Please update your bookmarks!

Now in our 13th year of bringing you beautiful imagery from biomedical science every day

Search the archive of over 4000 images

Building Permission

Hyaluronic acid from muscle stem cells interrupts debris-clearing immune cells allowing muscle injury repair to proceed

04 September 2022

Building Permission

When a muscle fibre, like the one shown, is injured, its associated stem cells, like the one coloured pink, are keen to start rebuilding. But, they must wait until immune cells have finished clearing up debris. In fact, the immune cells send ‘wait’ signals to the stem cells preventing their activity. Stem cells are impatient, though, and as soon as an injury occurs, they start producing and covering themselves with hyaluronic acid (coloured pale green and seen outlining the stem cell). This carbohydrate goo gradually thickens until it's dense enough to interrupt the immune cells’ signals, essentially giving the stem cells the go-ahead to start work. As humans age, production of hyaluronic acid diminishes, which may explain why injuries in older people take so long to repair. Without a thick gooey barrier to block the immune signals, the stem cells are forced to wait, their building permit denied.

Written by Ruth Williams

Search The Archive

Submit An Image

Follow on Tumblr

Follow on Instagram

What is BPoD?

BPoD stands for Biomedical Picture of the Day. Managed by the MRC Laboratory of Medical Sciences until Jul 2023, it is now run independently by a dedicated team of scientists and writers. The website aims to engage everyone, young and old, in the wonders of biology, and its influence on medicine. The ever-growing archive of more than 4000 research images documents over a decade of progress. Explore the collection and see what you discover. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.

Read More

BPoD is also available in Catalan at www.bpod.cat with translations by the University of Valencia.