Fig. 3

A dense nerve fiber network penetrates and runs along arrector pili muscle (APM) fibers but rarely contacts the hair follicle epithelium. (a) A representative electron micrograph with segmentation showing APM (blue), nerve fibers (yellow), hair follicle epithelium (black), and cellular nuclei (green). (b–e) Three-dimensional (3D) reconstructions of muscle, nerve fibers, and the epithelium from two different angles showing few contacts between nerve fibers and the hair follicule epithelium (b, c). In contrast, the nerve fiber network runs along the APM (d, e). Scale bars: 10 μm.