The nature of Langerhans cells granules: an ultrastructural study.

Langerhans cells and macrophages have been studied in both oral lichen planus lesions and histiocytosis X. Many of the macrophages in both lesions contained phagolysosomes in various stages of degradation. Some of these phagolysosomes were found to develop slender processes and very narrow extensions containing little processed phagocytosed material. These latter structures were indistinguishable from Langerhans granules and were termed Langerhans granule-like structures. There is enough evidence in the present study to suggest that typical Langerhans granules evolve from Langerhans granule-like structures and to confirm that Langerhans cells are a type of macrophage which at one stage of their development show Langerhans granules.