Growth of follicles of various animals following ovarian grafting under the kidney capsules of immunodeficient mice.

Abstract

Aim: Various researchers have studied xenografting ovarian tissues into immunodeficient mice to accelerate the follicular growth of several mammalian species. In this study, the authors focused on the following three points in growing follicles in transplanted ovarian tissues under kidney capsules: the effects of the storage conditions of the donor ovarian tissues, the effects of donor age on the survival rates of grafted mouse ovaries, and the methods used to grow the follicles of xenografted bovine ovaries. Methods and Results: When ovaries stored for 0, 6, 12 or 24h at 4°C and at room temperature were transplanted under the kidney capsules of immunodeficient mice, fewer mouse and rabbit grafts survived following 24h storage. The survival rates of bovine grafts were relatively low for all storage times. When mouse ovaries were held for 24h at 4°C or at room temperature, low-temperature storage effectively improved the survival rates of the grafts. Although the survival rates of grafted genital ridges containing premeiotic germ cells from fetuses and grafted ovaries from mice 0, 10, 20, 40 and 80days after birth were similar among donors of different ages, the cleavage rate of oocytes following insemination was significantly lower in the grafts from the ovaries of 80-day-old mice. Antral follicles formed in surviving bovine ovarian grafts. Cumulus-oocyte complexes were collected from the grafted ovaries of fetuses and calves, and the oocytes reached the metaphase II stage following culture, but they did not develop to the pronuclear stage after in vitro fertilization. Conclusion: Our findings provide basic data on xenografting ovarian tissues into immunodeficient mice to accelerate the growth of follicles. (Reprod Med Biol 2008; 7: 45-54).