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

Paws or Wings?

Understanding more about the genes controlling limb development in mammals and birds

08 January 2019

Paws or Wings?

Although they might look very different on the surface, a chicken and a mouse are surprisingly similar under the skin. Both are tetrapods, meaning that they have four limbs, although birds have wings rather than front legs, and the same cluster of genes controls the growth and development of wings and legs in both animals. These pictures show the activity of three of these genes, known as Hox genes, in the front leg of a mouse embryo developing in the womb (top) or the wing of a chick growing inside an egg (bottom). Crucial differences in the switches that turn Hox genes on and off control the patterns of gene activity in each species and the resulting limb shapes. Intriguingly, one switch is much more similar in chickens and bats than bats and mice, suggesting that it might be responsible for generating wings in birds as well as flying mammals.

Written by Kat Arney

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.