caa a22 4500 469084170 CHVBK 20180323133000.0 cr unu---uuuuu 170328e19920801xx s 000 0 eng 10.1007/BF00319629 doi (NATIONALLICENCE)springer-10.1007/BF00319629 Rademakers L. Division of Histochemistry and Electron Microscopy, Department of Pathology, University Hospital, P.O. Box 85500, NL-3508 GA, Utrecht, The Netherlands aut Dark and light zones of germinal centres of the human tonsil: an ultrastructural study with emphasis on heterogeneity of follicular dendritic cells [Elektronische Daten] [L. Rademakers] Summary: The cellular composition of the dark and light zones of germinal centres in human tonsils was quantitatively determined by electron microscopy. In addition to the well known germinal-centre B-cells, we defined the cleaved blast as a new distinct cell type in the germinal centre. The dark and the light zones clearly differed in their content of lymphoid and non-lymphoid germinal-centre cells. The dark zone was characterized by higher frequencies of cleaved blasts and small centroblasts, a higher blast-centrocyte ratio and a higher incidence of mitotic figures. In contrast, the light zone had higher frequencies of centrocytes, centroplasmacytoid cells, lymphocytes and follicular dendritic cells (FDC) and an inverted blast-centrocyte ratio. Seven distinct appearances of FDC (FDC.1-FDC.7) could be recognized on the basis of their ultrastructure. The distribution pattern of these subtypes differed between the dark and light zone. The undifferentiated subtypes FDC.2 and FDC.3 predominated in the dark zone. In contrast, the highly differentiated subtypes FDC.4 and FDC.5 were present at a much higher density in the light zone. These findings suggest that the dark and light zones are different compartments with regard to proliferation and differentiation of germinal-centre B-cells and that both compartments have a specific microenvironment influenced by FDC. Springer-Verlag, 1992 Tonsil nationallicence Germinal centre nationallicence Dark zone nationallicence Eight zone nationallicence Follicular dendritic cells nationallicence Man nationallicence Cell and Tissue Research Springer-Verlag 269/2(1992-08-01), 359-368 0302-766X 269:2<359 1992 269 441 https://doi.org/10.1007/BF00319629 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00319629 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Rademakers L. Division of Histochemistry and Electron Microscopy, Department of Pathology, University Hospital, P.O. Box 85500, NL-3508 GA, Utrecht, The Netherlands aut NATIONALLICENCE 773 0- Cell and Tissue Research Springer-Verlag 269/2(1992-08-01), 359-368 0302-766X 269:2<359 1992 269 441 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer