Microinjection refers to the process of using a glass micropipette

Micropipette

A micropipette is one of two different instruments used in science laboratories.-History:The first micropipette was patented in 1960 by Dr Hanns Schmitz . The founder of the company Eppendorf, Dr...

 to insert substances at a microscopic

Microscopic

The microscopic scale is the scale of size or length used to describe objects smaller than those that can easily be seen by the naked eye and which require a lens or microscope to see them clearly.-History:...

 or borderline macroscopic

Macroscopic

The macroscopic scale is the length scale on which objects or processes are of a size which is measurable and observable by the naked eye.When applied to phenomena and abstract objects, the macroscopic scale describes existence in the world as we perceive it, often in contrast to experiences or...

 level into a single living cell

Cell (biology)

The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

. It is a simple mechanical process in which a needle roughly 0.5 to 5 micrometers in diameter penetrates the cell membrane

Cell membrane

The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...

 and/or the nuclear envelope

Nuclear envelope

A nuclear envelope is a double lipid bilayer that encloses the genetic material in eukaryotic cells. The nuclear envelope also serves as the physical barrier, separating the contents of the nucleus from the cytosol...

. The desired contents are then injected into the desired sub-cellular compartment and the needle is removed. Microinjection is normally performed under a specialized optical microscope

Optical microscope

The optical microscope, often referred to as the "light microscope", is a type of microscope which uses visible light and a system of lenses to magnify images of small samples. Optical microscopes are the oldest design of microscope and were possibly designed in their present compound form in the...

 setup called a micromanipulator

Micromanipulator

A micromanipulator is a device which is used to physically interact with a sample under a microscope, where a level of precision of movement is necessary that cannot be achieved by the unaided human hand...

. The process is frequently used as a vector

Vector (molecular biology)

In molecular biology, a vector is a DNA molecule used as a vehicle to transfer foreign genetic material into another cell. The four major types of vectors are plasmids, viruses, cosmids, and artificial chromosomes...

 in genetic engineering

Genetic engineering

Genetic engineering, also called genetic modification, is the direct human manipulation of an organism's genome using modern DNA technology. It involves the introduction of foreign DNA or synthetic genes into the organism of interest...

 and transgenics to insert genetic material into a single cell. Microinjection can also be used in the cloning

Cloning

Cloning in biology is the process of producing similar populations of genetically identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually. Cloning in biotechnology refers to processes used to create copies of DNA fragments , cells , or...

 of organisms, and in the study of cell biology and viruses. Microcapillary and microscopic devices are used to deliver DNA into a protoplast.

Examples

• Microinjection is used as a vector in transgenic plant production.
• Microinjection of genes into fertilized eggs
  Ovum
  An ovum is a haploid female reproductive cell or gamete. Both animals and embryophytes have ova. The term ovule is used for the young ovum of an animal, as well as the plant structure that carries the female gametophyte and egg cell and develops into a seed after fertilization...
  
   is a common vector used in the production of higher forms of transgenic animals
  Genetically modified organism
  A genetically modified organism or genetically engineered organism is an organism whose genetic material has been altered using genetic engineering techniques. These techniques, generally known as recombinant DNA technology, use DNA molecules from different sources, which are combined into one...
  
  .
• Microinjection of a gene knockdown
  Gene knockdown
  Gene knockdown refers to techniques by which the expression of one or more of an organism's genes is reduced, either through genetic modification or by treatment with a reagent such as a short DNA or RNA oligonucleotide with a sequence complementary to either an mRNA transcript or a gene...
  
   reagent such as a morpholino
  Morpholino
  In molecular biology, a Morpholino is a molecule in a particular structural family that is used to modify gene expression. Morpholino oligomers are an antisense technology used to block access of other molecules to specific sequences within nucleic acid...
  
   oligo into eggs
  Egg (biology)
  An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
  
   or early zygotes is commonly used to probe the function of a gene
  Gene
  A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
  
   during development of embryos.