BLyS localization by immunoelectron microscopy. The figure shows an ultrastructural immunocytochemistry for golgin (A-C) and BLyS (D) within G-CSF–treated neutrophils, using specific primary monoclonal antibodies and gold-labeled secondary antibodies (15-nm gold particles). All images were obtained from the same experiment. (A-C) Cells are stained with uranyl acetate and lead citrate to enhance the contrast and to allow better visualization of cell morphology and ultrastructure. (B) Area of panel A at higher magnification. (A-B) Areas marked by squares represent vesicles of Golgi complexes. (C-D) Golgian fields at high magnification and the absence of BLyS immunoreactivity in granules (indicated by “g”). Scale bars: (A) 750 nm; (B) 350 nm; (C-D) 200 nm. All images were obtained from a representative experiment of 4 performed with similar results. Original magnification: A, 6300 ×; B, 15 750 ×; C, D, 20 000 ×. Images were acquired using a Zeiss EM 10 electron microscope (Zeiss, Oberkochen, Germany); magnification and numerical aperture of the objective lens, 30 micron; gold-labeled sections were stained with uranyl acetate and lead citrate; images were directly photographed by the microscope, using film from Eastman Kodak Company (New York, NY). EM images were digitized using the ACSee 5.0 Software (ACD System Ltd., Victoria, British Columbia, Canada), and composed in Corel Draw 12.0 (Corel Corporation, Sapphire Court, Berkshire, UK).