Langerhans Granules in Fetal Keratinocytes

Langerhans granules, as reconstructed in three dimensions and interpreted by Sagebiel and Reed (13) and Wolff (17), are discs that in profile look like rods bounded by limiting membranes 50-60 A wide and terminated in vesicular formations. Internally, the rod-shaped portions of the disc demonstrate paracrystalline nets or lattices with a periodicity of 90 A . The presence of these granules has been considered the primary criterion by which dendritic cells have been identified as Langerhans cells . Although Langerhans granules are most commonly seen in dendritic cells in the epidermis (3-5), they have been found in cells in the dermis (18), in the epithelia of the uterine cervix (7) and of the gingiva (14), and in three forms of histiocytosis X granulomata (1, 8, 15) . Langerhans granules have now been found inside the keratinocytes of fetal epidermis .