Intracytoplasmic sperm injection
From Free net encyclopedia
Image:Icsi.JPG Intracytoplasmic sperm injection (ICSI) is an in vitro fertilization procedure in which a single sperm is injected directly into an egg; this procedure is most commonly used to overcome male infertility problems.
The procedure is done under a microscope using micromanipulation devices (micromanipulators, microinjectors and micropipettes). A holding pipette (on picture on left) stablizes the mature oocyte. from the opposite site a thin, hollow needle is pierced into the inner part of the oocyte, the oolemma. it is loaded with a single sperm that will be released into the oocyte. The pictured oocyte has an extruded polar body at about 12 o'clock indicating its maturity. After the procedure, the oocyte will be placed into cell culture and checked on the following day for signs of fertilization.
In natural fertilization sperm compete and when the first sperm enters the egg cell, the egg cell blocks the entry of any other sperm. Concern has been raised that in ICSI this sperm selection process is bypassed and the sperm is selected by the embryologist without undergoing any specific testing.
There is some suggestion that birth defects are increased with the use of IVF in general, and ICSI specifically. (see section of IVF discussing birth defects)
References
- Kurinczuk JJ. Safety issues in assisted reproduction technology Human Reproduction 2003;18:925-31. PMID 12721163.
- Maher ER. Imprinting and assisted reproductive technology. Human Molecular Genetics 2005;14(suppl):R133-8. PMID 15809265.