Microinjection of cells: basic considerations

At least four types of technological advances have made cell microinjection procedures precise and practical, while minimizing negative impacts on cell viability: 1) hydraulic and electromechanical (stepper) micromanipulators, which provide operators with precise spatial control; 2) high-precision syringe and automated pneumatic microinjectors, with high reproducibility in the injected volume; 3) regulated pipet-pulling devices that yield highly reproducible tip diameters, down to 0.1 microns; and 4) specially adapted microscopes in both upright and inverted configurations, which ensure high-quality observation of cellular features in brightfield and all modern contrasting techniques, while reducing movement-induced vibrations at the contact point with the cell.