A new method for comparative light and electron microscopic studies of individual cells, selected in the living state.

A method is described which permits comparative light and electronmicroscopic studies of cell cultures, cell spreads or single selected cells which have been kept in the Plastic Film Dish (PFD). The PFD is a versatile large surface tissue culture chamber which, for electron microscopy, is mounted with a transparent FEP-Teflon film bottom. Cells are observed, selected and marked on the PFD-bottom with a high power inverted light microscope. The cells are fixed and dehydrated with a semi-automatic device while they are still in situ in the PFD. During the preparation steps for electron microscopy the topographical relationship between individual cells and between cells and cell support is accurately retained. After embedding and polymerization the Teflon film is easily peeled off the polymerized Epon, leaving a replica of the mark around the selected cell. This permits relocation of the selected cells for ultrathin sectioning in a plane plan-parallel to the original cell support. To enable orientated sectioning of selected cells in a plane perpendicular to the cell support, cells are tagged with Letraset-letters after original embedding and polymerization. Subsequently the re-embedded polymerized specimens are orientated in the microtome in a position which permits controlled thin sectioning of the tagged cells in the previously selected plane.