Triggering of final oocyte maturation in ovarian stimulation

Georg Griesinger, Efstratios Kolibianakis


Oocyte maturation is the process by which the oocyte completes the first meiotic division and progresses to metaphase II. Human oocytes are arrested at the prophase of the first meiotic division, and are held in this meiotic arrest by the surrounding mural granulosa cells. This lasts until the preovulatory luteinizing hormone (LH) surge triggers the resumption of meiosis in the fully grown oocyte, which is approximately 100 µm in diameter (Figure 21.1). Mural granulosa cells express LH receptors, in contrast to the cumulus cells and the oocyte itself. Thus, the mechanism by which LH stimulates resumption of meiosis is indirect. LH stimulates meiotic maturation by inducing the expression of epidermal growth factor-like proteins in the mural granulosa cells. The mural granulose cells then act on the cumulus cells, which in turn trigger oocyte maturation. The signaling pathway between the cumulus cells and the oocyte itself is, however, poorly understood. Due to the fact that the metaphase II oocyte has a relatively short lifespan, the timing of maturation must be tightly regulated for fertilization to occur. Occurrence of spontaneous LH surge in unstimulated cycles is inconsistent while there is lack of a spontaneous LH surge in cycles stimulated with gonadotropins and gonadotropin-releasing hormone (GnRH) analogues. For this reason human chorionic gonadotropin (hCG) is uniformly used in infertile couples to trigger final oocyte maturation, in order to schedule sexual intercourse, intra uterine insemination, or oocyte retrieval for in vitro fertilization (IVF).

Original languageEnglish
Title of host publicationOvarian Stimulation
Number of pages11
PublisherCambridge University Press
Publication date01.01.2010
ISBN (Print)9780521197359
ISBN (Electronic)9780511762390
Publication statusPublished - 01.01.2010


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