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.

鸟胚中的刚毛结构来自于被称为基板（placode）的微小皮肤细胞结构，基板顶端快速增殖的细胞环形成了刚毛的圆柱井结构。