Sequential production of Birbeck granules through adsorptive pinocytosis.

A case of vitiligo with inflammatory raised borders was observed electron microscopically, resulting in an interesting view of the formation of Birbeck granules in Langerhans cells. Following the formation of larger coated vesicles, which perform adsorptive pinocytosis from the cell membrane, membrane invagination of the cell occurred shown as the tubular infolding, resulting in the observation of the characteristic Birbeck granule band pattern in its interior. This phenomenon supports the theory of Hashimoto and Tarnowski (1968) that Birbeck granules are formed from the infolding of the cell membrane. In addition, our study shows the involvement of adsorptive pinocytosis in the formation of the granules. It was suggested that when the coated Birbeck granule shifts into the cell, possibly its coat is detached and the vesicle portion forms the globule of the Birbeck granule.