Merkel cells participate in the induction and alignment of epidermal ends of arrector pili muscles of human fetal skin.

The follicular proximal ends of arrector pili muscles anchor the bulge areas of human hair follicles. However, the location of the ends of these muscles towards the epidermis, especially the fine points of attachment, is not fully understood. Conventional serial sections of the scalp skin of a 12-month-old infant were examined. Most of the distal ends were situated in the upper dermis, while some seemed to be in close contact with the epidermal basal layers. In vertical sections of the scalp skin of 36-week-old fetus, double immunoenzyme staining showed a close topographic correlation between the epidermal ends of the arrector pili muscles and the epidermal and dermal Merkel cells. These findings allow speculation that fetal Merkel cells participate in the induction and alignment of arrector pili muscles.