We’re all hairy. Hair covers almost all of our bodies, from the flowing locks on our heads to the delicate wisps on our arms and legs. Far from being purely cosmetic, mammalian hair evolved millions of years ago as protection from the cold – long before any cave-person thought of sticking a bone through it and going on the hunt for a date. Pictured, dyed blue and green, is a bed of tiny mouse hair follicles, the organs in mammalian skin from which hairs sprout. Arrector pili muscles (stained red and pink attached to the follicles) pull the hair upright in cold weather to produce ‘goose bumps’ – trapping a layer of air next to the skin for warmth. At the base of each follicle is a round blue structure called ‘the bulge’ where stem cells are nurtured before being released into the follicle to produce new, luxuriant, hair growth.
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.
BPoD is also available in Catalan at www.bpod.cat with translations by the University of Valencia.