Mouse oocyte meiotic resumption and polar body extrusion in vitro are differentially influenced by FSH, epidermal growth factor and meiosis-activating sterol
Source: Human Reproduction, Volume 19, Number 12, December 2004 , pp. 2913-2918(6)
Publisher: Oxford University Press
Abstract:BACKGROUND: In this study, we compared the relative ability of FSH (100 mIU/ml), epidermal growth factor (EGF) (10 ng/ml), and follicular-fluid meiosis-activating sterol (FF-MAS, 10 mol/l) to induce meiotic resumption and polar body I (PBI) extrusion in mouse oocytes. METHODS: Cumulus-enclosed oocytes (CEO) were co-incubated with meiosis-arresting agents, including 4 mmol/l hypoxanthine (Hx), 0.3 mmol/l dibutyryl cAMP (dbcAMP), and 8.5 mol/l cilostamide, a selective inhibitor of the oocyte-specific phosphodiesterase 3 (PDE 3). RESULTS: In Hx-treated oocytes, FSH, EGF and FF-MAS induced meiosis resumption at very high rates, but only FSH and EGF also promoted PBI extrusion with high frequency. In experiments conducted in the presence of dbcAMP, FF-MAS was unable to promote an increase in germinal vesicle breakdown (GVBD) rate, whereas FSH and EGF generated a response similar to the Hx groups. Neither FSH, EGF nor FF-MAS caused any change in the meiotic status of CEO when meiotic arrest at the germinal vesicle (GV) stage was maintained by cilostamide. In the presence of Hx, naked oocytes (NkO) co-cultured with their cumulus cells were able to respond to the GVBD-inducing effect of FSH and EGF by resuming meiosis at high rate. CONCLUSIONS: Collectively, these results indicate that: (i) a signal triggered in cumulus cells by either FSH or EGF, but not necessarily coincident with FF-MAS, may contribute to meiotic maturation, supporting GVBD and extrusion of PBI; (ii) the transmission of this signal can occur in a paracrine fashion, at least with reference to the breakdown of the GV. It also appears that concomitant regulation of intra-oocyte cAMP degradation is a prerequisite for meiosis resumption.
Document Type: Research Article
Affiliations: 1: TECNOBIOS Procreazione, Bologna, 40125, 2: Department of Biomedical Sciences and Technologies, 3: Novo Nordisk A/S, Copenhagen, 2820, Denmark, 4: Department of Experimental Medicine, University of L'Aquila, L'Aquila, 67010, Italy, 5: University of Bologna, 40125, Bologna, Italy and 6: Department of Obstetrics & Gynaecology, University of Sydney, Sydney, NSW 2145, Australia
Publication date: 2004-12-01
- Human Reproduction features full-length, peer-reviewed papers reporting original research, clinical case histories, as well as opinions and debates on topical issues. Papers published cover the scientific and medical aspects of reproductive physiology and pathology, endocrinology, andrology, gonad function, gametogenesis, fertilization, embryo development, implantation, pregnancy, genetics, genetic diagnosis, oncology, infectious disease, surgery, contraception, infertility treatment, psychology, ethics and social issues. The highest scientific and editorial standard is maintained throughout the journal along with a rapid rate of publication.