An electron microscopy method for imaging thick samples with high resolution is published online this week in Nature Methods.
Electron tomography allows for three-dimensional (3D) reconstruction of cellular structures and thus provides a window into how cells are organized and how they function. One way samples are prepared for electron tomography is by cutting frozen cells into thin sections (300 nanometers or less) and then imaging each section separately.However, reconstructing the entire structure from thin sections is laborious, and thicker sections cannot be used because images of them are typically blurred. This is mitigated to some extent in scanning transmission electron tomography, in which a tightly focused electron beam is used, but the image quality from the bottom of thick sections still remains poor.
Richard Leapman and colleagues found that, with a different detector configuration on a scanning transmission electron microscope, they can image samples that are more than three times the thickness of typical samples at high resolution. Using this method on red blood cells infected with Plasmodium falciparum, a parasite that causes malaria, high-resolution 3D reconstructions of entire cells was generated by serially imaging just a few thick sections. The intricate system of membranes of red blood cell and parasite, as well as several organelles, can be seen in detail.
Most electron microscopes should be easily modified to accommodate this altered detector configuration. The approach should prove useful for the 3D reconstruction of entire mammalian cells.