In the bird embryo these bristles erupt from tiny patches of skin cells called placodes. A ring of fast-growing cells on the top of the placode builds a cylindrical wall that becomes a bristle.

Result: the texture of integumentary cells, the shape and size of hair socket and bristle were important characters for species identification.

Using materials such as polymers with pores no wider than a toothbrush bristle, researchers have learned to sculpt scaffolds in shapes into which cells can settle.