Expression of GM-CSF and GM-CSFRα in tonsillar lymphoid follicle. (A) Immunostain of GM-CSF. Some positive lymphocytes are scattered in the germinal center, but the distinct reticular pattern was not found. Counterstained with methyl green. Original magnification × 90. (B) Immunostain of GM-CSFRα. The distinct lacy pattern is found in the light zone and often in the outer and mantle zones. MZ, mantle zone; ALZ, apical light zone. Counterstained with methyl green. Original magnification × 240. (C) Immunoelectron micrograph of GM-CSFRα on FDC. Note a positive reaction on the surface of binucleated FDC embracing lymphocyte (L) of FDC. Bar = 1 nm. Original magnification × 5,700. (D) In situ hybridization of GM-CSFRα oligonucleotide. Dendritic-shaped cells are heavily labeled. Uncounterstained. Original magnification × 386.