Are LXRs Involved in Regulation of Human Oocyte Meiosis Resumption?

In mice deficient of Liver X Receptor (LXR) genes, the oocytes are unable to resume meiosis. Oxysterols are molecules derived from the cholesterol synthesis pathway. They are ligands of the liver X receptors (LXRs). In human, the LXR signalling pathway has never been investigated in this process. The Investigator propose to analyse in granulosa cells surrounding ovocyte the expression of LXR, their target genes and the enzymes involved in oxysterols synthesis. These granulosa cells are normally retrieved and destroyed 18 hours after sperm insemination of oocytes in a In Vitro Fertilization program. The oocyte meiosis resumption will be considered as positive (Granulosa cell positive, GC+) if a zygote is observed 18 hours after sperm insemination and negative (Granulosa cell negative, GC-) if none zygote appears. Moreover the investigator will analyse the quality of embryo development during 5 days after zygote is formed (normal process of In Vitro Fertilization) . The both populations of granulosa cells (GC+ and GC-) will be compared. The measurements of Liver X Receptor genes and the enzymes involved in oxysterols pathways xill be performed by Reverse Transcription-Polymerase Chain Reaction. The accumulation of lipid in granulosa cells will be measures by oil red staining. By this sudy the investigator will probably find new biological markers of resumption meiosis for women enrolled in In Vitro Fertilization programm. Moreover, data will help to better understand the physiopathology of oocyte meiosis failures.