Sweating profusely at the gym may seem an inconvenience, but this behaviour is crucial to temperature regulation. Both sweat glands (the round green-tagged protrusion at the top of the picture) and hair follicles (in pink) are found all over our bodies, a major advantage enabling us to survive hot climates and exercise. In most other mammals, they occur on separate body parts. Studying the hairy backs and sweaty paws of mice revealed that these structures depend on two opposing signalling pathways: high levels of a molecule known as BMP promote the growth of sweat glands while suppressing another signal, SHH, required for hair follicles to develop. In humans, these signals are separated in time, so hair follicles appear first, followed by a surge in BMP levels triggering the development of sweat glands. These findings could pave the way for improved skin grafts, which currently do not include sweat glands.
Written by Emmanuelle Briolat