Medical Research Council - London Institute of Medical Sciences

Now in our 9th year of bringing you beautiful imagery from biomedical science every day

Leaving a Trace

Pinpointing when the barrier between the brain and the bloodstream forms

05 November 2019

Leaving a Trace

Your brain is hungry, constantly demanding a supply of nutrients and oxygen that are brought in by a dense network of blood vessels. But your brain is also precious and needs to be protected from harmful chemicals that might have got into the bloodstream. This is the job of the blood-brain barrier – a protective layer that acts as a filter between the brain and the bloodstream. To find out more about how this barrier forms during development, researchers are studying tiny transparent zebrafish. These pictures show the networks of blood vessels (pink) forming inside the brains of living fish embryos ranging from three days (left) to ten days old (right), which have had different coloured and sized fluorescent tracer molecules injected into their blood. The tracers leak out from the blood vessels in the younger embryos but not the older ones, helping to pinpoint the time when the barrier forms.

Written by Kat Arney

Search The Archive

Submit An Image

What is BPoD?

BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. 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 with translations by the University of Valencia.