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. 2001 Aug;159(2):501–512. doi: 10.1016/S0002-9440(10)61722-1

Figure 1.

Figure 1.

A–C: Variable distribution of surface IgD-positive B cells in individual specimens (ABC technique on autoclaved paraffin sections using polyclonal anti-human IgD). A: Strongly IgD-positive recirculating B cells occupy the mantle zones of two tangentially sectioned secondary follicles. In this case strongly IgD-positive cells are densely distributed in the inner MZ, obscuring the memory B cells that are only weakly positive for surface IgD. Strongly IgD-positive B cells occur in the outer MZ and extend along the PALS (top left) as a small stripe. Final magnification, ×55. B: Strongly IgD-positive recirculating B cells form a small mantle zone in the secondary follicle. The inner MZ is occupied by weakly IgD-positive memory B cells mixed with few strongly IgD-positive cells. The outer MZ is hardly recognizable. There are only few strongly IgD-positive B cells at the periphery of the PALS (left). Final magnification, ×88. C: A broad IgD-positive mantle zone surrounds the unstained germinal centers of two secondary follicles. The memory B cells of the inner MZ are IgD-negative in this specimen. A prominent ring-like accumulation of strongly IgD-positive B cells is seen in the outer MZ, whereas fewer of these cells are scattered in the inner MZ. Strongly IgD-positive B cells are almost absent at the periphery of the PALS. Final magnification, ×55. D: Distribution of CD34 in a secondary follicle. Few endothelia and perivascular fibroblasts are stained in the follicle interior. CD34 is not detected between the mantle zone and the MZ, indicating absence of a marginal sinus. A few capillary endothelia are reactive in the perifollicular zone. Weakly CD34-positive sinus endothelia occur only in this region. ABC technique on paraffin section using mAb QBend10. Final magnification, ×110. E: B lymphocytes stained for CD79a. All compartments of the secondary follicle are positive. The reactivity is most pronounced in the outer MZ. ABC technique on autoclaved paraffin section using mAb JCB117. Final magnification, ×69. F: Smooth muscle α-actin in a secondary follicle: A network of strongly actin-positive branched cells divides the inner MZ from the outer MZ. In this specimen a relatively large part of the outer MZ contains actin-positive cells. More weakly stained cells are present in the perifollicular zone. The actin-positive branched cells continue into a network filling the entire PALS (right). The red pulp also harbors some actin-positive cells. ABC technique on autoclaved paraffin section using mAb asm-1. Final magnification, ×88. G: Thrombomodulin in a primary (or tangentially sectioned secondary) follicle. Thrombomodulin-positive branched cells occur at the border between inner MZ and outer MZ and continue into the PALS (left). Red pulp sinus endothelia are also thrombomodulin-positive, especially in the perifollicular region. ABC technique on paraffin section using mAb TM 1009. Final magnification, ×69.