title: The role of perivitelline space abnormalities of oocytes in the developmental potential of embryos.
abstract: OBJECTIVE
  In assisted reproductive technology (ART), high embryo quality is closely related to high-quality oocytes. Cytoplasmic maturation and extracytoplasmic maturation are the most important components in determining oocyte quality. One of the most important components of extracytoplasmic maturation is perivitelline abnormalities. The aim of this study is to determine the effect of perivitelline abnormalities on the development of high-quality embryos.
  
  
  METHODS
  The study material consisted of 217 of 1154 oocytes from 98 intracytoplasmic sperm injection (ICSI) cycles undertaken due to male factor infertility. Only cycles with long gonadotropin-releasing hormone analogs combined with recombinant Follicle-stimulating hormone (rec-FSH) were included in study. We compared 105 metaphase-II oocytes that had dominantly perivitelline space abnormalities (large perivitelline space with or without granules) with 112 normal metaphase-II oocytes, based on the embryo grade determined by Alpha Scientists in Reproductive Medicine and the European Society of Human Reproduction and Embryology (ESHRE) Special Interest Group of Embryology. Normal metaphase-II oocytes were characterized by a round, clear zona pellucida; a small perivitelline space containing a single unfragmented first polar body; and a pale, moderately granular cytoplasm with no inclusions.
  
  
  RESULTS
  The development rates of Grade I, II, and III embryos were 68.5%, 23.8%, and 7.7%, respectively, in the 105 oocytes with perivitelline abnormalities. The development rates of Grade I, II, and III embryos were 82.1%, 17.9%, and 0%, respectively, in the 112 morphologically normal oocytes. When compared with normal oocytes, Grade I (68.5% vs. 82.1%, p value; 0.019) and Grade III (7.7% vs. 0%, p value; 0.003) embryo development rates were significantly lower in oocytes that had perivitelline abnormalities.
  
  
  CONCLUSIONS
  It is important to analyze oocyte quality using multiple parameters, including the perivitelline space. Perivitelline space abnormalities might negatively affect embryo development in male factor-infertile couples that are stimulated with rec-FSH. Therefore, when choosing embryos for transfer, we must take into consideration the historical oocyte data.
authors.affiliation: Department of Obstetrics and Gynecology, Eskişehir Osmangazi University Faculty of Medicine, Eskişehir, Turkey.
authors.forename: Hikmet
authors.initials: H
authors.lastname: Hassa
authors.affiliation: Department of Obstetrics and Gynecology, Eskişehir Osmangazi University Faculty of Medicine, Eskişehir, Turkey.
authors.forename: Yunus
authors.initials: Y
authors.lastname: Aydın
authors.affiliation: Department of Obstetrics and Gynecology, Eskişehir Osmangazi University Faculty of Medicine, Eskişehir, Turkey.
authors.forename: Fulya
authors.initials: F
authors.lastname: Taplamacıoğlu
keywords: Embryo; oocyte; perivitelline space