Why are we the size that we are? And why don’t our organs keep growing once we’re reached adulthood? The answers to these questions are still mostly a mystery, although scientists are gradually figuring out the genes that control how big animals or their body parts grow. The chief culprits are genes called Salvador, Warts and Hippo, which work together with others to tell organs to grow to the right size. The three strange-looking objects shown here are fruit fly wing discs – primitive structures in a maggot that will eventually grow into wings in the adult insect. Top left is a normal-sized disc, while the other two – shown at the same scale – come from animals with changes in two genes that interact with Hippo and its molecular colleagues. Scientists studying these supersized flies hope to understand how human cancer cells manage to over-ride these growth controls and form large tumours.
Written by Kat Arney
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.