Microinjection of DNA, RNA and/or protein directly into the pronuclei of fertilized zygotes is the most extensively used method of gene transfer in the mouse.

The basic components of a microinjection workstation are an inverted microscope in the middle with a micromanipulator on either side. Microinjection of zygote pronuclei is most easily performed at a magnification of 400X and pronuclei are seen using differential interference contrast (DIC). Two micromanipulators are needed for controlling precisely the movement of both, the injection needle and the pipette that holds the embryo. The flow of genetic material in the injection pipette is controlled by an automatic injector. To obtain better embryo survival and successful injection, a pneumatic antivibration table is used to avoid any vibration on the microscope stage.