2009 Volume 44 Issue 4 Pages 252-256
Dark field imaging of scanning transmission electron microscopy (STEM) was applied to electron tomography (ET) method of biological specimens. Theoretical resolution of ET is reduced by chromatic aberration and unfocused information from the thick section. STEM imaging has effective advantages for these problems. We observed the thick biological specimens such as rat absorptive enterocyte using STEM. The reconstruction data from tilted image series (±70º) of the 250nm and 400nm thick plastic embedded specimens acquired by using 300kV STEM showed that the resolution reached to about 10nm in Z-axis. The slices from the reconstructions showed a clathrin hexagonal lattice structure on the coated pit or hexagonal array of actin filaments within microvilli parallel actin bundle even in the ZX plane. These values are close to the theoretical Z-axis resolutions that are estimated to 10nm or 15nm. It should be noted that these resolutions were obtained even in the peripheral region of the reconstructions. Therefore, we concluded that dark field STEM imaging improves the electron tomography resolution throughout the whole reconstructions not just the center of tomogram especially in thick sections.
