Ultrastructural Analysis of CFSC-2G Cells

Electron microscopic analysis of CFSC-2G cells was essentially conducted as described before [6 (link)]. In brief, cells were fixed in 1× phosphate buffered saline (PBS) containing 3% glutaraldehyde, washed in 0.1 M Soerensen’s phosphate buffer (Merck, Darmstadt, Germany), and fixed in a solution of 1% osmium tetroxide (OsO₄) (Roth, Karlsruhe, Germany) solved in 25 mM sucrose buffer (Merck). Fixed cells were dehydrated and subsequently incubated in propylene oxide (Serva, Heidelberg, Germany) in a mixture of Epon resin (Serva) and propylene oxide (1:1) and pure Epon. Finally, ultrathin sections (70–100 nm) were prepared and packed upon Cu/Rh grids (HR23 Maxtaform, Plano GmbH, Wetzlar, Germany). Contrast was enhanced by staining with 0.5% uranyl acetate and 1% lead citrate (both Science Services, Munich, Germany). The samples were analyzed at an acceleration voltage of 60 kV using a Zeiss Leo 906 (Carl Zeiss AG, Oberkochen, Germany) transmission electron microscope and depicted images were taken at magnifications of 2156× to 35,970×.