In vitro maturation (IVM) is the technique of letting the contents of ovarian follicles and the oocytes inside mature in vitro. It can be offered to women with infertility problems, combined with IVF, offering women pregnancy without ovarian stimulation. In 1935, Pincus & Enzmann did the first experiment on immature rabbit oocyte, showing in vitro spontaneous maturation and fertilization. They showed maturation occurs in isolation from normal follicular environment. In 1965 Edwards then continued IVM studies in mouse, sheep, cow, pig, rhesus monkey and human. By 1991, the first pregnancy was recorded using IVM followed by IVF, and in 1994 the first birth using IVM oocytes from polycystic ovarian syndrome patients was recorded highlighting that PCOS patient's oocytes are capable of maturation.
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If a follicle has reached the early tertiary or antral stage, IVM can be carried out. Firstly, the oocytes need to be obtained from the subject. The timing of this is dependent on the stage of the cycle the subject is in, which is usually monitored using ultrasonography. If without the use of priming, oocytes are obtained when the largest follicles are around 10mm in size. In humans, this can be done with an aspiration needle, using ultrasound to allow accuracy. Depending on whether you are aspirating mature or immature follicles, the protocol differs slightly. In both procedures the aspiration pressure is reduced, but to varying degrees. Additionally, it is more important that the aspirate is filtered when retrieving immature follicles, as the follicles are much smaller and harder to see in the fluid extracted
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Once the oocytes have sufficiently matured, they can then be fertilised in vitro, known as in vitro fertilisation (IVF). Techniques such as intracytoplasmic sperm injection (ICSI) can also be utilised to improve the chances of fertilisation being successful, which should be performed at least one hour (and optimally two to four hours) after the first polar body extrusion. Out of in vitro matured oocytes, those fertilised with ICSI have a success rates of 60-80%, compared to IVF with success rates of 25-40%. A few live births have already been made by taking small early tertiary follicles, letting them mature in vitro and subsequently fertilizing them. However, for follicles that haven't reached the early tertiary stage, IVM is still under development.
There are a lot of cellular changes in the oocyte and the rest of the cells in the follicle, which makes it very susceptible. Nevertheless, it is possible to let a primordial follicle mature to a secondary follicle outside the body by growing it in a slice of ovarian tissue. The subsequent maturity from secondary to early tertiary stage can then be supported in test-tubes. It has been suggested that photoirradiation of granulosa cells and oocytes may facilitate IVM
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Read more : In Vitro Maturation Clinics Log on to : http://www.ferty9.com/in-vitromaturation/