Have you ever wondered how your nails keep growing, even when you bite or bash them? Look at a nail and you will see a white, half-moon near the base known as the matrix. Here new cells are continuously being produced, growing towards the tip, underneath the nail to form a layer called the nail bed. Cells on the nail bed produce keratin, the same hard protein that forms our hair, and the claws, hooves and horns of animals. Keratin-containing cells flatten as they age, then die, and this becomes the hard nail. Nails on the hands protect the fingertips, enhance fine touch, and are used for scratching. This image shows regrowth over six months after the nail had to be removed following a bone injury. The matrix can be seen clearly on the bottom row.
Written by Julie Webb
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.