One of the most important factors for successful ovarian graft transplantation is the rapid establishment of a rich blood supply, which is crucial for survival of the ovarian follicles. Without vascular anastomosis, grafts are solely dependent on posttransplantation vascularization. Dissen et al. showed that transplanted immature rat ovaries become profusely revascularized within 48 h after autotransplantation. Vascular growth was accompanied by increased expression of genes that encode the angiogenic factors, vascular endothelial growth factor (VEGF), and transforming growth factor-^1 (TGFp-1). An important issue in ovarian transplantation is follicle survival. Transplantation of fresh mouse ovaries resulted in 50% reduction in follicle numbers. In another study, only 35% of the oocytes survived fresh sheep tissue grafting into SCID mice. In both studies, the grafts were transplanted into the well-vascularized kidney capsule. buy lipitor cheap
Prior to revascularization, implants are vulnerable to is-chemia-reperfusion injury, which is the main obstacle to the survival of a tissue after transplantation. Kim et al. showed a 30%-70% reduction in graft size and significant fibrotic changes within most grafts. There is a direct correlation between the size of the follicles and their susceptibility to insufficient blood supply, namely, larger antral follicles invariably undergo degeneration while smaller ones survive. Most of the damage occurs mainly during the first few days after transplantation.