Presence of bile acids in human follicular fluid and their relation with embryo development in modified natural cycle IVF

Evidence from several species indicates that the initial stages of follicular growth proceed very slowly. In contrast, the stages after antrum formation are much more rapid. Atresia seems to be most prevalent as follicles approach the size at which they could be recruited for potential ovulation. Although most follicles become atretic around that stage, a few are recruited into a cohort or wave of follicles that continue to grow beyond the stage at which atresia normally occurs. Next, a species-specific number of follicles is selected for dominance. In some species (e.g. rats, primates, pigs), dominant follicles develop only during the follicular phase and are thus destined for ovulation. In another group of species (e.g. cattle, sheep, horses), recruitment, selection, and dominance occur at regular intervals, but only the dominant follicle present during the follicular phase ovulates. There is evidence that the mechanism that allows some follicles to be recruited for potential dominance/ovulation is a small elevation in basal FSH that, by chance, occurs around the time the follicle would normally begin atresia. Some recruited follicles are saved from atresia for only a short time. Only the dominant follicle(s) selected from among the recruited follicles grows to ovulatory or near-ovulatory size. What determines which follicle(s) becomes dominant is not known, but dominance appears to be maintained by negative feedback effects of products of the dominant follicle on circulating FSH. Selection and dominance are accompanied by progressive increases in the ability of thecal cells to produce androgen and granulosa cells to aromatize androgen to estradiol.(ABSTRACT TRUNCATED AT 250 WORDS)

Mammalian reproduction hinges upon the timely ovulation of a fully differentiated oocyte. This event is the culmination of a complex and dynamic developmental relationship between the oocyte and the antral follicle housing it; the antral follicle constitutes a specialized microenvironment or niche, uniquely suited to the needs of the oocyte as it approaches ovulation. During this time, the oocyte must complete its final growth, capacitation, and nuclear and cytoplasmic maturation. Its microenvironment--the antral follicle--is in turn responsible for the integrity of these processes and the production of a high quality oocyte. Components of the antral follicle, including three distinct somatic cell types (theca, granulosa and cumulus), the basal lamina, and follicular fluid, each have active and regulatory roles in oocyte differentiation. Several milestones in antral folliculogenesis also have an influence on oocyte development. This review will discuss the antral follicle microenvironment with specific attention to its importance in oocyte differentiation. As assisted reproductive technologies (ART) often require stages of oocyte differentiation to occur in vitro rather than in vivo, current knowledge of the antral follicle microenvironment will also be discussed with respect to its clinical applications.

To determine whether metabolomic analysis of follicular fluid could prove a useful noninvasive technique for the selection of viable oocytes and embryos. Metabolomic analysis based on proton nuclear magnetic resonance ((1)H NMR) performed on follicular fluid collected from in vitro fertilization (IVF) patients. A university research center and a private fertility clinic. Fifty-eight women undergoing IVF treatment. Follicular fluid collected at the time of oocyte retrieval. Metabolomic profile, assessment of oocyte developmental potential and embryo viability. The metabolomic profile of follicular fluid from follicles where the oocyte resulted in a fertilized egg that failed to cleave (n = 9) was distinctly different from that where oocytes developed into early cleavage-stage embryos. Discriminating metabolites included glucose, lactate, choline/phosphocholine, and lipoproteins. Comparison of follicular fluid from women who subsequently had a positive β human chorionic gonadotropin (n = 10) to those who were unsuccessful in achieving a pregnancy (n = 12) revealed metabolic differences that were correlated to cycle outcome. Differences in the metabolite composition of follicular fluid correlate with the developmental competence of the human oocyte. Therefore, metabolomic profiling of follicular fluid may prove to be an important technique in gamete/embryo selection. Copyright © 2012 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.