Hair Development and Langerhans Cell Migration During Human Embryogenesis

The study investigated the migration and development of Langerhans cells (LC) and melanocytes in relation to hair follicles during human embryogenesis. Using 4-mm punch biopsies from 38 aborted fetuses, it was found that melanocytes completed their migration to the epidermal compartment before 16 weeks gestation (WG), while LC first appeared at 16 to 18 WG. Hair follicle buds and immature LC were observed in the back and abdomen, and LC were also found in the acrosyringial area of the sole at 16 to 19 WG. The findings suggested that LC develop immunoregulatory properties at the hair follicle site, which is an immune-privilege site, during embryogenesis.