Microinjection refers to the process of using a glass micropipette to insert substances at a microscopic or borderline macroscopic level into a single living cell. It's a simple mechanical process in which a needle roughly 0.5 to 5 micrometers in diameter penetrates the cell membrane and/or the nuclear envelope. The desired contents are then injected into the desired sub-cellular compartment and the needle's removed. Microinjection's normally performed under a specialized optical microscope setu… (More on Microinjection)