Does women's age influence zona pellucida birefringence of metaphase II oocytes in in-vitro maturation program?

ABSTRACT

In vitro maturation [IVM] is a promising treatment option for certain infertile women. Nowadays, with the aid of PolScope, it has become possible to evaluate zona pellucida [ZP] characteristics as a parameter of oocyte quality. Moreover, quality of oocytes can be influenced by many factors, such as patient's age. The PolScope system is a non-invasive technique to assess birefringent structures such as the meiotic spindle and ZP in living oocytes. The aim was to determine the influence of the woman's age on ZP birefringence, a sign of oocyte quality, and morphology of in-vitro matured human oocytes using non-invasive polarized light [PolScope] microscopy. ZP birefringence and morphology were determined in 105 retrieved oocytes from 58 women undergoing ICSI in two age groups [>/= 30 years and <30 years]. The immature oocytes were selected and after IVM, the quality of metaphase II [MII] oocytes was assessed. The oocytes abnormalities were classified as intracytoplasmic and extracytoplasmic abnormalities. Oocyte maturation rates were significantly reduced in >/= 30 year's women [56%] in comparison with other age group [80.7%]. In addition, the ZP birefringence was significantly higher in MII oocytes in the younger group compared with the older group [76.2% vs.38.1%; p=0.00]. Following morphologic assessment, the rates of oocytes with extracytoplasmic [p=0.02] and both abnormalities [extra- and intracytoplasmic] [p=0.01] were higher in aged versus the younger women. There was a positive relationship between advanced maternal age with decreased ZP birefringence and oocyte morphological quality in in-vitro matured human oocytes