You’re looking at some of the most detailed images of live nerve endings ever captured by a technique called SNAP-tagging.
Scientists from European Molecular Biology Laboratory (EMBL) have published images, in which it’s possible to make out individual nerves and touch receptors in unprecedented detail.
Above: This image shows that free nerve endings [red] in the skin split into an incredible number of branches. Credit EMBL/S. Morley
Top: A bundle of nerves that relays information from touch receptors on the skin to the spinal cord and ultimately the brain, imaged with the new technique. Credit EMBL/L.Castaldi
The technique, called SNAP-tagging, relies on a small protein that ‘binds to a specific small chemical structure – and once bound, it won’t let go.’
Paul Heppenstall of a new technique developed by his lab, said:
“Already we’ve been able to see things that we couldn’t see before. Structures such as nerves arranged around a hair on the skin; we can now see them under the microscope, just as they were presumed to be. If we’d gone straight for the mouse, there would have been fewer challenges!”
“But we tried to do everything step-by-step. So we started with cell culture, and found that the probes are very sticky – you have to wash the cells repeatedly to get rid of tags that are floating around, not attached to SNAP, before you can see anything. Then we took tissue from animals, and tried to label that, and they were still sticky. And then finally we got around to injecting into the mouse – and it just worked! It turns out that the mouse is very good at washing out what it doesn’t need – so all the probes get washed out, except the ones bound to SNAP.”