Microinjection

Microinjection is the use of a glass micropipette to inject a liquid substance at a microscopic or borderline macroscopic level.

Microinjection can also be used in the cloning of organisms, in the study of cell biology and viruses, and for treating male subfertility through intracytoplasmic sperm injection (ICSI, /ˈɪksi/ IK-see).

This system typically requires a regulated pressure source, a capillary holder, and either a coarse or a fine micromanipulator.

A pulsed flow system, however, allows for greater control and consistency over the amount of sample injected: the most common arrangement for intracytoplasmic sperm injection includes an Eppendorf "Femtojet" injector coupled with an Eppendorf "InjectMan", though procedures involving other targets usually take advantage of much less expensive equipment of similar capability.

The pronuclear injection of mouse sperm is one of the two most common methods for producing transgenic animals (along with the genetic engineering of embryonic stem cells).

Microinjection of a fluorescent dye into Ciona intestinalis eggs positioned in a microwell array.
Diagram of the intracytoplasmic sperm injection of a human egg. Micromanipulator on the left holds egg in position while microinjector on the right delivers a single sperm cell.