Morphological criteria of oocyte quality

In vitro fertilization technology consists of the selection and fertilization of oocytes, the production and transplantation of embryos to recipients. The quality of oocytes has a direct impact on the fertilization and developmental competence of oocytes. Criteria that show the quality of oocytes are subdivided into morphological, cellular, and molecular. The aim of this article was to review the morphological criteria that are used for estimation of the quality of oocytes before their fertilization in vitro. These criteria include the evaluation of the structure of oocyte: cumulus complex, oocyte cytoplasm, polar body, perivitelline space, zona pellucida, and meiotic spindle.