Cytogenetic Analysis ofIn VivoandIn VitroMatured Oocytes Derived from Naturally Cycling and Stimulated Mice

Abstract

The objective of the study was to analyze the potential role of follicle stimulating hormone (FSH) in cytogenetic changes of in vivo and in vitro matured mouse oocytes and to determine whether the lower developmental potential of immature oocytes is due to a higher incidence of abnormalities in meiotic spindle organization and chromosome alignment as well as aneuploidy. In vivo matured oocytes were collected from naturally ovulated and superovulated (5.0 I U of recombinant follicle-stimulating hormone [rec-FSH] þ recombinant human chorionic gonadotropin [rec-HCG]) mice. Immature oocytes were retrieved from naturally cycling mice and from mice primed with rec-FSH for 48 h. The immature oocytes were cultured 18 h for in vitro maturation (IVM). In vivo and in vitro matured oocytes were assessed for the meiotic spindle organization and chromosome alignment as well as aneuploidy. There was no significant difference of meiotic spindle organization, chromosomal alignment and aneuploidy between in vivo and in vitro matured oocytes derived from naturally cycling and stimulated mice. Therefore, the lower developmental potential of immature oocytes does not appear to be directly related to the incidence of abnormal meiotic spindle organization and chromosome alignment or to aneuploidy.

Does Ovulation Induction Increase the Risk of Aneuploid Conception? Comparison of First Trimester Miscarriages after FSH Stimulated Cycles and Naturally Conceived Cycles

“…FSH may rescue abnormal oocytes and facilitate the meiotic resumption of these oocytes, which otherwise may be destined for atresia (14). Recent data demonstrated no difference between exogenous FSH exposure and embryonic aneuploidy, which was compatible with our results (13,14,(16)(17)(18)(19). In our study, total FSH dose and cycle-day 3 FSH levels were similar in patients with abnormal and normal karyotypes.…”

Trisomic pregnancy and elevated FSH: implications for the oocyte pool hypothesis

“…In mouse oocytes matured in vitro (Roberts et al, 2005), exposure to elevated concentrations of FSH in culture is associated with increased aneuploidy and premature separation of sister chromatids. Another study (Xu et al, 2008), however, showed no difference between mature oocytes from natural cycles and immature oocytes, also from natural cycles, cultured in a solution of FSH and luteinizing hormone. A study in infertile women (Gras et al, 1992) compared aneuploidy rates in unstimulated cycles with aneuploidy rates in cycles stimulated with (i) human menopausal gonadotrophin (which contains FSH) and other hormones or (ii) a buserelin (GnRH agonist) flare.…”

High follicle-stimulating hormone increases aneuploidy in human oocytes matured in vitro

“…In Xu et al (18), there is no difference between in vivo and in vitro matured oocytes derived from both naturally cycling and stimulated mice. Only a single dose of 5.0 IU of recombinant FSH was injected for the purpose of stimulation or FSH priming before IVM.…”