Reduction of progesterone receptor expression in human cumulus cells at the time of oocyte collection during IVF is associated with good embryo quality

Background: It has been reported that the progesterone receptor (PR) level is transiently increased within the follicle by LH stimulation and controls cumulus cells in follicles and oocyte maturation. The purpose of this study was to predict developmental competence of human oocytes during IVF via analysis of PR in cumulus cells surrounding mature oocytes. Methods: Prior to oocyte retrieval, the follicular diameter was measured and follicular fluid was collected from each mature follicle. Cumulus cells were manually separated from the oocyte-cumulus complex under a microscope. PR and PR mRNA were assessed by immunohistochemistry and real-time quantitative polymerase chain reaction (RT-PCR) measurement in human cumulus cells. Results: Immunoreactive PR-A was mainly localized in the cytoplasm and PR-B was localized in the nuclei. There was no significant relationship between PR expression and follicular diameter, follicular fluid concentration of steroids, or LH. There was no significant relationship between expression of PRs and fertilization or cleavage rate. However, PR expression was lower in the good morphology group (blastomeres ≥7 cells with fragmentation ≥5% on day 3) when compared to the other groups (P<0.05). Conclusions: These results suggest that follicular LH or steroids do not affect PR expression, and full reduction of total PR expression on cumulus cells at the time of oocyte collection is associated with good morphology in human oocytes.