Instruments and Techniques
Imaging in Tissue and Living Animals
Confocal and 2-photon microscopy are the microscopy techniques of choice when it comes to imaging specimens thicker than about 10 microns since they offer excellent suppression of background light. Using 2-photon microscopy allows researchers to image 100 microns and deeper in tissue or on the live animal. Optical clearing sample preparation techniques can make particularly demanding (fixed) samples accessible to these microscopy techniques.
Imaging Living Cells
Live cells cultured on cover slips can be imaged well with confocal, spinning disk and regular (camera-based) widefield microscopes. Microscopes with integrated incubators allow automated live-cell imaging for 48 hours and longer. TIRF (total internal reflection) microscopes provide means to image events at the cell surface at particularly low photo-toxicity and high sensitivity.
Imaging Flow Cytometry allows to for the sorting of cells based on morphological features instead of pure signal levels.
Resolving Sub-cellular Structures
Subcellular structures down to the ~200 nm level (about the diameter of a mitochondrion) can be resolved well in confocal and widefield microscopes. To resolve smaller structures, super-resolution microscopes have been developed: structured illumination microscopy (SIM) provides multicolor 3D super-resolution images at down to 100 nm resolution. For even higher resolution, STED microscopes and FPALM/PALM/STORM instruments are available.