TEM Tomographic Analysis of the Capillary Wall
Stereopair viewing of thick sections is limited to a single viewing angle and the overlapping of structures in two-dimensional images recorded from thick sections obscures details. Serial section analysis of ultrathin sections is limited to small sampled regions and difficult to obtain ribbons of 5-10 nm sections. Electron tomography overcomes these limitations by using sections of sufficient thickness to contain a significant fraction of endothelial vesicular structures. It also resolves the surperposition of features by computing a three-dimensional reconstruction from digital slices only a few nanometers thick. Image aquisition in tomography consists of electron projections collected at different angles into a series of 2D images. In a computer this process is reversed by a back projection algorithm resulting a three-dimensional representation of the original structure.