FIGURE 12.

A: a collection of bronchial lymphoid tissue with a lymphoid follicle containing a germinal center (GC) surrounded by a rim of darker-staining lymphocytes that extend to the epithelium of both the small airway and alveolar surface (Movat's stain, ×6). B: another follicle, in which the germinal center stains strongly for B cells (×6). C: a serial section of the same airway stained for CD4 cells, which are scattered around the edge of the follicle and in the airway wall (×6.5). D: an airway that has been extensively remodeled by connective tissue deposition in the subepithelial and adventitial compartments of the airway wall. The arrow points to the smooth muscle that separates the subepithelial from the adventitial compartments (Movat's stain, ×6). [From Hogg et al. (40), with permission from Massachusetts Medical Society.]