Introduction OHSS still remains a complication of assisted reproduction treatments. hCG administration to trigger final oocyte maturation will release vascular mediators, being VEGF and other proteins such as VE-Cadherin or Angiopoietin- 2. It has been shown that replacing hCG by GnRH agonists will induce a very short endogenous LH peak, potent enough to induce final oocyte maturation but no OHSS will develop. The investigators examined VEGF, VE-Cadherin and Angiopoietin-2 modulation by hCG as well as GnRH agonists in oocyte donors undergoing controlled ovarian stimulation.

Material and Methods Between June and December of 2008 we evaluated 90 egg donors. They underwent COH with 150 IU rFSH as starting dose, we separated them in 3 groups (n:30 each): Groups 1 and 2 received a 0.25mg daily dose of GnRH antagonist when a follicle 14mm in diameter was observed. hCG 250g was given to group 1 while group 2 received triptorelin 0.2mg when leading two follicles were 17mm. Group 3 was stimulated with standard long protocol, hCG was given following similar criteria.

Blood was collected the day of hCG/aGnRH administration as well as the day of egg retrieval, and follicular fluid from the first two mature follicles was also frozen. We collected granulosa cells (GC) of 10 patients of each group as well Levels of VEGF, sVE-Cadherin an Angiopietin 2 were determined by ELISA in serum and in follicular fluid.

Results were analyzed via ANOVA.Data are expressed as mean± SEM. A significant difference was defined as p< 0.05.

Inclusion Criteria:

• Donors

Exclusion Criteria:

• Important diseases

oocyte Donors

• Age between 18 and 35 years and previous pregnancy
• Regular menstrual cycles (between 25 and 35 days)
• Normal karyotype
• Body massindex between 18 and 25 kg/m2
• Negative serology for VHB, VHC and HIV
• Normal cervical cytology in the past year, and a vaginal ultrasound without evidence of any pathologic conditions