TABLE 2.
An overview of the imaging techniques used to study the structure and composition of cell-cell adhesions with electron and X-ray microscopy; TEM: transmission electron microscopy; FFEM: freeze-fracture electron microscopy; PREM: platinum replica electron microscopy; ET: electron tomography; VEM: volume electron microscopy; SBF-SEM: serial block face scanning electron microscopy; FIB-SEM: focused ion beam scanning electron microscopy; SXT: soft X-ray tomography; immuno-EM: immuno electron microscopy.
| Imaging technique | Resolution | Sample thickness | To investigate cell-cell adhesion and availability | Cons | In vivo imaging |
|---|---|---|---|---|---|
| TEM | xy: 2 nm | 60–80 nm | Ultrastructure of the tissue at a nanometer resolution, morphology of junctions, relationship with the actin cytoskeleton, measuring intermembrane space | Some technical handling and sample preparation optimization | Not possible |
| Correlation with LM possible | |||||
| Easily accessible and widely used | |||||
| FFEM and PREM possible | |||||
| ET | xy: 2 nm | Up to 300 nm | Filament arrangement within junctions, binding interactions between substructures, quantitative measurements | Some technical handling and sample preparation optimization | Not possible |
| Easily accessible and widely used | |||||
| VEM (including SBF-SEM and FIB-SEM) | xy: up to 5 nm | Up to 20 µm per day | Junctions and ultrastructure in volume, quantification possible, relationship between different junctions and its localization on the membrane surface | Technically demanding and sample preparation optimization necessary | Not possible |
| z: up to 5 nm | Limited availability, expensive machines | ||||
| SXT | xy: 10–50 nm | 10 µm | Junctions at a nanometer resolution in the near-native state and possible to reconstruct the ultrastructure of the cell in 3D; Correlation with LM possible | Technically demanding and sample preparation optimization necessary | Not possible |
| z: 10–50 nm | Limited availability because need for synchrotron | ||||
| Immuno-EM | Same as TEM | Same as TEM | Individual proteins and the ultrastructure of the sample in a nanometer resolution | Some technical handling and sample preparation optimization | Not possible |
| Easily accessible and widely used |