A glance at the human body and it all looks fairly symmetrical. But look closer and you’ll see a world of asymmetry, from a slightly sloping eyebrow through to the shapes and positions of our organs. The diaphragm too is in on the asymmetrical act. When we breathe out, it rises unevenly. But why? Is it just making do with the space around it? Researchers looked to mice for answers. Imaging the nerves that stimulate the diaphragm – the left and right phrenic nerves (pictured) – they found them to be asymmetrical. Using mutant mice they found this asymmetry was controlled by differences in the genes activated in these nerves. These genetic differences caused different signalling molecules to be activated in the left and right sides of the diaphragm. This might explain why some muscle disorders only affect one side of the diaphragm.
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.
BPoD is also available in Catalan at www.bpod.cat with translations by the University of Valencia.