[Ultrastructural observations on B cells in the human synovial membrane]

Two cellular type, A and B cells, are evident in the intimal layer of the human synovial membrane. The Authors studied the B-cells that show in their cytoplasm some secretory granules that are still unknown. In the normal synovial membrane of human knee, with transmission electron microscopic techniques, the relationship between the B-cells and the blood capillary vessels and some morphological features of the secretory granules, are studied. The blood capillary vessels have a continuous cellular wall, surrounded by a basal membrane. Typical features of the B-cells are the marked development of the rough endoplasmic reticulum, the Golgi apparatus and dense secretory vesicles. The B-cells appear to constitute some specific secretory cells, but its function has yet to be determined.