Can Stimulation Protocols Improve Oocyte Quality?
Ovarian follicle development in humans is a lengthy process that takes several months. Initial follicle recruitment from the resting pool is regulated by intraovarian factors and independent of circulating gonadotropin concentrations. Once follicles have initiated growth, they progress through a slow preantral growth phase (approximately 4 months) during which the formation of zona pellucida, granulosa cell layers, theca cell layers, and vascularization of the theca externa are accomplished (for review, see Richards 2001). The preantral growth stages are mainly under paracrine/autocrine control but the somatic cells already express the receptors for gonadotropins (Sokka et al. 1996; Oktay et al. 1997). Although the growth of preantral follicles are considered to be gonadotropin-independent, there are arguments that gonadotropin fluctuations may effect these early growing follicles (Parrot and Skinner 1998a,b). Along the lengthy track of follicle growth, granulosa cells are stimulated by a variety of factors such as epidermal growth factor (EGF), insulin-like growth factor-1 (IGF-1), basic fibroblast growth factor (bFGF), transforming growth factor α (TGF-α) and keratinocyte growth factor (KGF).
KeywordsGranulosa Cell GnRH Agonist Antral Follicle Keratinocyte Growth Factor Human Oocyte
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- Child TJ, Gulekli B, Tan SL (2001) Success during in vitro maturation (IVM) of oocyte treatment is dependent on the numbers of oocytes retrieved which are predicted by early follicular phase transvaginal ultrasound measurement of the antral follicle count and peak ovarian stromal blood flow velocity. Hum Reprod 16 (Abstract Book 1): 41CrossRefGoogle Scholar
- de Ziegler D, Jaaskelainen AS, Brioschi PA, Fanchin R, Bulletti C (1998) Synchronisation of endogenous and exogenous FSH stimuli in controlled ovarian hyperstimulation ( COH ). Hum Reprod 13: 561–564Google Scholar
- Gougeon A (1996) Regulation of ovarian follicular development in primates: facts and hypotheses. Endocrine Rev 17: 121–155Google Scholar
- Host E, Mikkelsen AL, Lindenberg S, Smidt-Jensen S (2000) Apoptosis in human cumulus cells in relation to maturation stage and cleavage of the corresponding oocyte. Acta Obstet Gynecol Scan 79: 936–940Google Scholar
- McNatty KP, Smith DM, Makris A, Osathanondh R, Ryan KJ (1979) The microenvironment of the human antral follicle: interrelationships among the steroid levels in antral fluid, the population of granulosa cells, and the status of the oocyte in vivo and in vitro. J Clin Endocrinol Metab 49: 851–860PubMedCrossRefGoogle Scholar
- Mikkelsen AL, Smith SD, Lindenberg S (1998) In vitro maturation of immature human oocytes. Hum Reprod 13 (Abstract Book 1): 23–24Google Scholar
- Schats R, Schoemaker J (2001) The use of GnRH agonists. In: Gardner, Weissman A, Howles C, Shoham Z (eds) Textbook of assisted reproductive technology. Martin Dunitz, London, pp 483–491Google Scholar
- Schipper I, Hop WC, Fauser BC (1998) The follicle-stimulating hormone (FSH) threshold/window concept examined by different interventions with exogenous FSH during the follicular phase of the normal menstrual cycle: duration, rather than magnitude, of FSH increase affects follicle development. J Clin Endocrinol Metab 83: 1292–1298PubMedCrossRefGoogle Scholar
- Smitz J, Nogueira D, Cortvrindt R, de Matos DG (2001) Oocyte in vitro maturation: state of the ART and basic requirements. In: Gardner, Weissman, Howles, Shoham (eds) Textbook of assisted reproductive technology. Martin Dunitz LTD, London, pp 107–137Google Scholar