Anatomy

Physics

Vesicle

Pathology

Nanotechnology

Scanning transmission electron microscopy

Microvesicles

Membrane

Staining

Biology

Gene

Optics

Biophysics

Microscopy

Negative stain

microRNA

Transmission electron microscopy

Chemistry

Materials science

Nanoparticle tracking analysis

Exosome

Morphology (biology)

Electron tomography

Electron microscope

Cell biology

Genetics

Biochemistry

Medicine

Ultrastructure

Journal of Visualized Experiments

Exosomes are nano-sized extracellular vesicles secreted by body fluids and are known to represent the characteristics of cells that secrete them. The contents and morphology of the secreted vesicles reflect cell behavior or physiological status, for example cell growth, migration, cleavage, and death. The exosomes' role may depend highly on size, and the size of exosomes varies from 30 to 300 nm. The most widely used method for exosome imaging is negative staining, while other results are based on Cryo-Transmission Electron Microscopy, Scanning Electron Microscopy, and Atomic Force Microscopy. The typical exosome's morphology assessed through negative staining is a cup-shape, but further details are not yet clear. An exosome well-characterized through structural study is necessary particular in medical and pharmaceutical fields. Therefore, function-dependent morphology should be verified by electron microscopy techniques such as labeling a specific protein in the detailed structure of exosome. To observe detailed structure, ultrathin sectioned images and negative stained images of exosomes were compared. In this protocol, we suggest transmission electron microscopy for the imaging of exosomes including negative staining, whole mount immuno-staining, block preparation, thin section, and immuno-gold labelling.

Sample Preparation and Imaging of Exosomes by Transmission Electron Microscopy