Cell culture techniques, large molecule

There are different methods to measure transepithelial permeability in tissues and cell cultures, e.g., the lanthaniun tracer technique, radio-isotope techniques using extracellular tracers and light microscopy techniques with large polar molecules, such as fluorescein isothiocyanate (FITC)-dextrans with an average molecular weight of at least 4 kD, or the use of electrophysiological methods such as TEER measurements. 

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