In vitro maturation

In vitro maturation (IVM) is the technique of letting ovarian follicles mature in vitro.

Techniques available

The abilit of in IVM depends on how mature the follicle already is. There are several stages in folliculogenesis, starting with a primordial follicle, which then becomes a primary, secondary, early tertiary (antral), late tertiary and eventually a preovulatory follicle.If a follicle has reached the early tertiary or antral stage, IVM can be carried out. A few live births have already been made [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11255547&dopt=Citation NCBI:In vitro maturation of oocytes. Hardy K, Wright CS, Franks S, Winston RM] ] 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.

Applications

*Facilitate IVF. Before an IVF, an ovarian stimulation is usually performed. By injecting gonadotropins, multiple ovaries will mature. However, with IVM, ovarian stimulation isn't essential. Rather, oocytes can mature outside the body prior to IVF. Hence, no (or at least a lower dose of) gonadotropins have to be injected in the body [http://www.sst.dk/publ/Publ2006/KOT/kunstig_befrugtning/Vejl_ivf_oa_dec06.pdf Vejledning om kunstig befrugtning 2006 (Danish)] ] . However, there still isn't enough evidence to prove the effectiveness and security of the technique.

*For research. There are a million of oocytes in the ovary at birth, but only about 400 of these will be ovulated. The rest will die by Ovarian follicle atresia. When oocytes destined to die are extracted, IVM enables the maturation of these follicles. Thus, they can be studied to gather more information on folliculogenesis and oocyte maturation.

References