During controlled ovarian stimulation with a GnRH antagonist protocol, luteal-phase support with micronized progesterone and 17beta-estradiol seem to increase endometrial L-selectin ligand expression in the luminal endothelium.
Eleven patients underwent controlled ovarian hyperstimulation yielding seventy-two embryos for evaluation. Mean nitric oxide metabolite (NOx) levels in the insemination media (IM) were 2.6 times higher in embryos that progressed to blastocysts by culture day (CD) 5 than those that did not (p=0.009). A comparison of the ROC curves between morphologic predictors and NOx levels revealed a trend toward a stronger association of IM NOx with blastocyst formation.Improvements in in vitro fertilization (IVF) outcomes have largely been due to the generation of supernumary embryos allowing for multiple embryo transfer (ET). The development of extended embryo culture has resulted in increased implantation rates and the potential for reductions in multiple births through single ET (1,2). One of the major disadvantages, however, has been the worry that in approximately 40% of patients, embryos would not be available for transfer (3).Unfortunately, culture day (CD) 3 morphologic assessment is not optimal for the prediction of blastocyst progression on CD 5 (4-5). Investigators have therefore sought quantifiable objective measures of embryonic health with a focus on metabolic activity (6-11). One such metabolic factor, nitric oxide (NO), has been implicated in a variety of biological and reproductive processes including oocyte maturation, fertilization and embryonic progression (12). Gouge et al. (13) demonstrated that NO production is essential for embryonic progression in the murine model. Chen and colleagues showed that blastocyst development in culture is inhibited by L-NAME, an NO inhibitor, in a concentration-dependent manner and SNP, an NO donor, can effectively reverse this effect (14). These studies highlight the potential importance of NO in embryogenesis.
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