Morphologic Parameters and in vitro Maturational Competence of Human Immature Oocyte Obtained from Stimulated IVF Cycle

An, So Jung; Jee, Byung Chul; Moon, Jeong Hee; Lee, Jung Ryeol; Suh, Chang Suk; Kim, Seok Hyun

Abstract

OBJECTIVE
This study was performed to investigate whether cumulus morphology and oocyte diameter influence on in vitro maturation (IVM) of human germinal vesicle (GV) stage oocytes obtained from stimulated in vitro fertilization (IVF) cycles.
METHODS
Forty-one GV stage oocytes were obtained from 21 patients who received ovarian hyperstimulation and IVF. According to cumulus morphology before denudation, GV oocytes were classified into oocytes with dispersed cumulus cells (CCs) or compacted CCs. The diameters of denuded oocytes, both including and excluding the zona pellucida, were measured. All oocytes were cultured in commercial IVM medium. Maturation was defined as extrusion of the first polar body and the matured oocytes were inseminated by ICSI method.
RESULTS
Overall maturation and fertilization rate were 56.1% and 73.9%. Matured oocytes had significantly higher proportion of oocytes with dispersed CCs compared to oocytes failed to mature (91.3% vs. 55.6%, p=0.023). There were no significant differences of oocytes outer (155.7 micrometer vs. 152.4 micrometer, NS), inner (114.3 micrometer vs. 113.4 micrometer, NS) diameters and zona thicknesses (41.3 micrometer vs. 39.1 micrometer, NS) between matured and not-matured oocytes. In-vitro maturation rate of oocytes with dispersed CCs was significantly higher than which of oocytes with compacted CCs (67.7% vs. 20.0%, p=0.044). Oocyte diameters (outer and inner) and thicknesses were not related with maturational competence.
CONCLUSION
Our results suggest that in vitro maturational competence of GV stage oocytes obtained from stimulated IVF cycles is closely associated with the cumulus morphology but not oocyte diameter.