An introduction to scanning transmission electron microscopy for
parasitology samples
Abstract
Since its inception in the 1930’s, transmission electron microscopy
(TEM) has been a powerful method to explore the cellular structure of
parasites. TEM usually requires samples of < 100 nm thick and
with parasites being larger than 1 µm, their study requires resin
embedding and ultrathin sectioning. During the past decade, several new
methods have been developed to improve, facilitate and speed-up the
structural characterisation of biological samples, offering new imaging
modalities for parasitology. In particular, scanning transmission
electron microscopy (STEM) can be used to observe sample sections as
thick as 1 µm thus becoming an alternative to conventional TEM. STEM can
also be performed under cryogenic conditions in combination with
cryo-electron tomography providing access to the study of thicker
samples in their native hydrated states in 3D. This method, called
cryo-scanning transmission electron tomography (cryo-STET), was first
developed in 2014. This review presents the basic concepts and benefits
of the STEM methods and provides examples to illustrate the potential
for new insights into the structure and ultrastructure of parasites.