Recovery of Oocytes from Bovine Ovarian Tissue Transplanted in Nod Scid Mice
ABSTRACT Hormonal stimulation following xenografting of ovarian tissue into immunodeficient mice promoted antral follicle development. Efficient retrieval of oocytes contained in these antral follicles is crucial in implementing a protocol involving xenotransplantation for fertility preservation of cancer patients. Using a bovine model, our objective was to recover oocytes from calf ovarian tissue transplanted into immunodeficient mice. Fresh pieces of ovarian cortex, 1-2 mm3, from calves were placed in subcutaneous spaces of male NOD SCID mice. Hormonal treatments were 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, 4 IU of FSH or 1 IU of FSH for 14 days. Forty eight to 72 h after the last injection, mice were euthanized and ovarian grafts were recovered. Serial sections of hematoxylin and eosin stained grafts were used for classifying and counting follicles. Randomly selected unstained ovarian sections were immunostained for nuclear proliferation antigen to ascertain viability. Other grafts were used for oocyte retrieval. Recovered oocytes were stained with orcein to assess maturation. Recovery of grafts (%) was no different across treatment groups. Treatment with FSH plus LH enhanced follicular development, but did not improve oocyte recovery. Evidence of maturation was only observed after incubation in vitro. We conclude that oocytes can be retrieved from xenotransplanted bovine ovarian tissue.
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ABSTRACT: The aim of this study was to determine, with a bovine model, the appropriate interval for xenografted adult and newborn ovarian tissue to develop gonadotropin-responsive follicles. Controlled experiment. Academic research laboratory. Male non-obese diabetic (NOD) severe combined immunodeficient (SCID) mice (n = 20) were hosts of bovine ovarian tissue. Two dairy calves and one adult beef cow were donors of ovarian tissue. Newborn and adult bovine ovarian cortical pieces were transplanted to the SC space of intact male NOD SCID mice. Grafts were recovered after euthanasia at intervals after transplantation. Microscopic examination of histologic sections to determine proportions of growing follicles. There was an increase in the proportion of primary and secondary follicles on day 55 after surgery for the cow and on day 124 after surgery for calf tissue compared with nongrafted and xenografted ovarian tissues recovered at previous intervals. These observed increases were accompanied by decreases in proportions of primordial follicles. Results suggest a sudden increase in the proportion of primary and secondary follicles due to progressive development of primordial follicles. In the NOD SCID mouse, bovine follicles survived xenotransplantation and underwent development. A longer interval was required for ovarian follicular development in calf tissues compared with that in adult cow ovarian tissues after xenotransplantation.Fertility and Sterility 05/2005; 83 Suppl 1:1180-7. · 4.30 Impact Factor