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Molecular mechanisms regulating follicular recruitment and selection
R Webb1, B K Campbell, H A Garverick
1Division of Agriculture and Horticulture, School of Biological Sciences, University of Nottingham, Loughborough, Leicestershire, UK.
Journal of Reproduction and Fertility. Supplement
|February 29, 2000
Summary
Ovarian follicular growth relies on both external hormones and internal ovarian signals. Understanding the interplay of these factors is key to determining follicle development and preventing atresia.
Area of Science:
- Reproductive Biology
- Endocrinology
- Cellular Biology
Background:
- Ovarian follicular growth is a complex process influenced by gonadotropins and intraovarian factors.
- Follicular development occurs in gonadotropin-independent and -dependent phases, with FSH and LH playing critical roles.
Purpose of the Study:
- To elucidate the integrated mechanisms governing ovarian follicular growth and selection.
- To understand the roles of specific hormonal signals and intraovarian systems in follicle development.
Main Methods:
- Analysis of gene expression patterns (mRNAs) for key enzymes and receptors in granulosa cells.
- Investigation of the influence of peripheral gonadotropin concentrations on follicular cell gene expression.
- Examination of intraovarian systems like IGF and activin/inhibin in follicular dominance.
Main Results:
- Follicular recruitment is driven by FSH, with LH required for maturation to the preovulatory stage.
- Changes in gonadotropin receptor and steroid enzyme gene expression correlate with peripheral hormone levels.
- Follicular dominance appears linked to the expression timing of LH receptor (LHr) and 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) mRNA.
Conclusions:
- The integration of endocrine and intraovarian signals dictates follicle fate, determining progression to dominance or atresia.
- Specific intraovarian systems, such as IGFBP-2 regulation in cows, contribute to follicular dominance.
- Further clarification is needed on the precise mechanisms of dominant follicle selection.