Time course of follicular development after bovine ovarian tissue transplantation in male non-obese diabetic severe combined immunodeficient mice.

OBJECTIVE: 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.
DESIGN: Controlled experiment.
SETTING: Academic research laboratory. ANIMAL(S): 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. INTERVENTION(S): 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. MAIN OUTCOME MEASURE(S): Microscopic examination of histologic sections to determine proportions of growing follicles. RESULT(S): 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. CONCLUSION(S): 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.