Table 1. Comparison of different techniques used for MCP analysis.

Method	Strengths	Weaknesses	Specialized Equipment	Previous Works
Transmission Electron Microscopy (TEM)	•Relatively simple instrumentation, compared to other techniques •Sample preparation is fast and straightforward •Easy to see surface and shape morphology •History of use in the field	•Compartments appear collapsed due to sample preparation methods •Size analysis is slow compared to DLS, etc.	•Glow Discharge System •Transmission Electron Microscope	[21,23–25,31,33,38,41,43–54]
Ultra-thin section Transmission Election Microscopy (TEM)	•Can visualize compartments in native context (does not require purification) •History of use in the field	•Relatively slow and difficult sample preparation, requiring multiple pieces of specialized equipment •Cannot readily visualize surface morphology •In vivo images are difficult to analyze due to other cellular components •Due to the irregular shape of compartments, size determination using this method yields a wide distribution of apparent compartment diameters, skewing results	•Ultramicrotome •Transmission Electron Microscope	[8,16,17,20,23,25,31,34–37,41,43–46,52,55–57]
Scanning Electron Microscopy (SEM)	•Compartments appear more true-to-size (less collapsed) •Can visualize surface and shape morphology	•Compartments appear slightly collapsed •Staining with a metal coat can hide surface morphologies and alter apparent size •Sample preparation and imaging is relatively complex and requires multiple pieces of specialized equipment	•Glow Discharge System •Critical Point Dryer •Sputter Coater •Scanning Electron Microscope
Transmission Electron Cryo-microscopy (Cryo TEM)	•Compartments retain solution size, shape, and morphology the best	•Sample preparation and imaging is difficult •Contrast is low due to lack of staining	•Glow Discharge System •Plunge freezer •Cryo transfer holder •Transmission electron microscope	[22,58]
Dynamic Light Scattering (DLS), etc.	•The most rapid, high-throughput method for determining the size distribution of a population of compartments	•Does not provide information on morphology	•DLS, Zeta Sizer, other system	[41,48,52]

Table 1 lists the various techniques, along with their strengths and weakness, that are utilized in the MCP field and are assessed in this work. We have also included a brief list of specialized equipment necessary for each technique, and a list of previous works in the MCP field in which each technique was used. Our hope is that this will enable selection of the technique best-suited for each study.