Electron Microscopic Studies of Lymphoid Cells in the Rheumatoid Synovial Membrane

Abstract

Abstract The sublining layer of the rheumatoid synovium has been examined in the electron microscope. In this layer lymphocytes appeared to leave the blood by passing through the endothelial cytoplasm of venules and veins to form dense perivascular accumulations rich in either lymphocytes, plasma cells or both. Undifferentiated blast cells and plasmablasts were also observed in these collections. The finding of predominantly lymphocytic accumulations around some vessels and predominantly plasma‐cellrich accumulations in a similar distribution around others suggested that most of the lymphocytes were plasma cell precursors or B lymphocytes.