Apposition of enteric nerve fibers to plasma cells and immunoblasts in the mouse small bowel

Light (LM) and electron microscopy (EM) were used to investigate the structural relationship between enteric nerves and the population of immune cells in the mouse small bowel. By LM, the osmium-zinc iodide procedure was used for visualizing nerve fibers; the incidence of nerve-plasma cell contacts in the mucosa and submucosa was calculated to be approximately 4 times and, respectively, 3 times greater than would be expected by chance alone (P < 0.0001). EM revealed close, synaptic-like contacts between axonal varicosities and plasma cells or B immunoblasts. The results presented here provide systematic quantitative evidence that a structural foundation for communication between nerve fibers and B cells exists in the mouse small bowel.