Recovery of Oocytes from Bovine Ovarian Tissue Transplanted to NOD SCID Mice

HERNANDEZ-FONSECA, H. J.; BOSCH, P.; WININGER, J. D.; MASSEY, J. B.; CHO, H.; BRACKETT, B. G.

USA

Congreso; 57 Annual Meeting of the American Society for Reproductive Medicine; 2001

American Society for Reproductive Medicine

Objective: Xenotransplantation of ovarian tissue may become an alternative means for preservation of fertility of female cancer patients and for the preservation of endangered species. Hormonal stimulation following xenografting has been shown to promote antral follicle development. However, efficient retrieval of the oocytes contained in these antral follicles is a crucial step if this alternative is to have future clinical applications. The objective of this study was to recover oocytes from calf ovarian tissue transplanted into immunodeficient mice. Design: Prospective randomized study. Materials/Methods: Fresh ovarian cortico-medullary pieces, 1-2 mm3, from 6 1-week-old calves were placed in dorsal subcutaneous spaces of 6 to 8-week-old male NOD SCID mice (6 pieces/mouse, 15 mice). Hormonal treatment was initiated 3 days after surgery. Control mice (n = 3) received saline while treated mice (n = 4/group) received daily intraperitoneal injections of either 4 IU of FSH plus 4 IU of LH (Humegon, Organon, West Orange, NJ, USA), 4 IU of FSH (Follistim, Organon) or 1 IU of FSH. Hormones were given for 14 days and oocyte retrieval was 48 hr after the last injection. Mice were euthanized, ovarian grafts were recovered, and representative pieces were hematoxylin and eosin stained for classifying and counting follicles. Other grafts were used for oocyte retrieval under a stereomicroscope (40X) using microsurgical techniques to facilitate recovery of oocytes. Seven oocytes were immediately stained with orcein to assess maturation. Results: Recovery of grafts (37%) was similar among al groups. Histology revealed no effects of the hormonal treatments on follicular development. The number of oocytes recovered was similar in each group; on average, 1 oocyte was recovered from each graft. All oocytes were immature (GV stage) upon retrieval. Conclusions: We have shown the feasibility of retrieving oocytes from bovine ovarian tissue after being grafted for 20 days in NOD SCID male mice. The recovered oocytes were immature upon retrieval. Hormonal treatment of host mice used did not improve either oocyte recovery rates or follicular development. Future studies will involve in vitro maturation of recovered oocytes. Supported by: This study was supported by Reproductive Biology Associates and The University of Georgia.