Serial reconstruction of the characteristic granule of the Langerhans cell.

Three-dimensional models of individual granules in the same Langerhans cell were made after analyzing serial sections of human epidermis in the electron microscope. These models revealed that the granule is made up of a flattened or curved orthogonal net of particles which is bounded externally by a limiting membrane and which may be disc-shaped, cup-shaped, or combinations of both shapes. This variety of shapes accounts for the many configurations of the granule seen in individual electron micrographs. Usually, the granule has a vesicular portion at, or near one margin. This demonstration of the three-dimensional structure of the granule establishes the inaccuracy of previously used descriptive terms, the granule should be called simply the "Langerhans cell granule."