A light microscopical study of isolated follicular dendritic cell-clusters in human tonsils.

In order to re-examine the cellular structure of isolated FDC-culsters in the germinal centers of human tonsils, a light microscopical analysis was made. Approximately 14 FDC-clusters were recovered from one enucleated germinal center using the enzyme digestion technique. The minimum unit of the FDC-clusters was composed of one FDC and 8 to 9 lymphocytes. Most of the FDC-clusters were representative of the microenvironment of the light zone at the germinal center in situ. Half of the engulfed centrocytes were supposed to be at the Go phase, and the others at the G1 to G2 phase. It is suspected that the helper-T cell has some relationship to the FDC microenvironment, and that the suppressor-T cell does not. Most of the CIgG-containing cells in the germinal centers were considered to have infiltrated into the interspace of the FDC microenvironment.