Human Oocyte Abnormalities: Basic Analyses and Clinical Applications

Oocyte quality impacts early embryonic survival and the establishment and maintenance of pregnancy. Although meiosis may be completed succe­s­sfully, there are a variety of other processes occurring within the cytoplasm of the oocyte that are required for complete developmental competence following fertilization. Morphological criteria are insufficient to give information on the oocyte’s developmental ability, so it is of importance to understand the cellular and mole­cular basis of the oocyte pathology and determine the classification criteria for the selection of oocytes with superior developmental ability. In the absence of a comprehensive oocyte grading scheme, the power of morphological observations to aid oocyte/embryo sele­ction is reduced. Until the mechanisms underlying oocyte quality are elucidated, efforts to apply assisted reproductive technologies in the treatment of human infertility will not be maximized. Exciting new technologies and data on oocyte biology have emerged in the last few years. In the present review, we briefly consider morphological characteristics with regard to oocyte developmental competency and then summarize key cellular and molecular findings as related to the pathophysiology of human oocytes. Finally, we consider some possible clinical predictors for assessing oocyte quality in ART.