Is oocyte morphology prognostic of embryo developmental potential after ICSI?

Abstract

Metaphase II-stage oocytes collected from patients following ovarian stimulation show varying qualities. Both nuclear and cytoplasmic maturation have to be completed in a co-ordinated mode to ensure optimal conditions for subsequent fertilization. Disturbances or asynchrony of these processes may result in different morphological abnormalities, depending on whether nuclear or cytoplasmic maturation has been affected. In this respect it has been suggested that dysmorphic features occurring early in meiotic maturation may be associated with a higher frequency of aneuploidy and fertilization failure, while those occurring late in maturation may cause a higher incidence of developmental failure. In fact, more than half of the gametes collected show morphological abnormalities, some of which seem to be correlated with an impaired outcome (e.g. aggregation of endoplasmic reticulum, vacuolization, increased ooplasmic viscosity, giant eggs). Therefore, it is strongly recommended to include oocyte quality in all scoring systems applied in IVF laboratories.