Effects of Long-Term Grafting on Follicular Growth in Porcine Ovarian Cortical Grafts Xenoplanted to Severe Combined Immunodeficient (SCID) Mice

Abstract

Abstract. To establish a tool for the study of follicular growth and development, we xenotransplanted small pieces (approximately 1 mm 3 ) of porcine ovarian cortical tissues containing only primordial follicles and small preantral follicles under the capsules of kidneys of severe combined immunodeficient (SCID) mice (8-10 weeks old). The changes in cell proliferation and cell death/ apoptosis, and vascularization in xenotransplanted follicles during follicular growth and development were analyzed histochemically at 1-26 weeks after operation. Follicles in grafted ovarian tissues grew rapidly forming an antral cavity (a hallmark of tertiary follicles) at 1 week after grafting. The diameter of the follicles in transplanted tissues ranged from 0.5 to 1.5 mm, from 0.5 to 2.0 mm and from 0.5 to 3.0 mm at 1, 2 and 26 weeks after the operation, respectively. Histological observation of ovarian tissues at 26 weeks after grafting revealed that all grafts had abundant capillary vessels, which invaded from murine organs and surrounded the growing follicles. Grafted small preantral follicles developed to the antral stages at 1 week after grafting and growing antral follicles survived at 26 weeks after grafting. The oocytes in the growing follicles were easily recovered for evaluating the quality. Our simple xenografting sysytem is easy to use and a good experimental tool for the study of folliclular growth and development in porcine ovaries.

Growth and Maturation of Follicles and Oocytes Following Xenotransplantation of Porcine Ovarian Tissues and In Vitro Maturation

“…In the 8 weeks group, many tertiary follicles with large antral cavities were observed on the surface of the grafted tissues. As noted in our previous report [20], large tertiary follicles and a progressed and expanded neovascularization were seen on the surface of antral follicles in the 2 weeks group under the dissecting microscope. In the recovered ovarian tissues, some of the growing tertiary follicles with large and clear antral cavities had oocytes, which remained at the GV stage (Table 2).…”

“…The tissue pieces contained many preantral follicles, which were less than 0.3 mm in diameter. Then, as previously reported [20], they were xenotransplanted under the kidney capsules of adult female severe combined immunodeficient (SCID) mice, which lack T or B lymphocytes but not natural killer cells are considered to be an in vivo model of the human immune system, and are used as recipients for xenotransplantation, to establish an experimental model that provides fundamental information on follicular growth and development in grafted tissues and that aids in understanding the mechanisms of individual follicular growth and/or atresia. Based on our previous findings [20], oocytes that were more than 0.5 mm in diameter collected 2 and 8 weeks after xenotransplantation from growing tertiary follicles, in the xenotransplanted tissues of porcine ovaries were cultured for in vitro maturation (IVM) to assess the quality of each oocyte.…”

“…The stages of follicular development were defined as follows [20,21]. (1) follicle has an antrum and is more than 0.5 mm in diameter.…”

Effects of gonadotrophin treatments on meiotic and developmental competence of oocytes in porcine primordial follicles following xenografting to nude mice

“…Snow et al (2002) demonstrated that oocytes that grow within mouse ovarian tissue xenografted to nude rats acquire the ability to generate pups. Ovarian tissues have been prepared from species phylogenetically distant from mice, including humans (Oktay et al 1998, Weissman et al 1999, Kim et al 2002, Gook et al 2003, dogs (Metcalfe et al 2001), monkeys (Candy et al 1995), sheep (Gosden et al 1994), cows (Senbon et al 2003), pigs (Kaneko et al 2003, Kagawa et al 2005, tammar wallaby (Mattiske et al 2002) and common wombats (Cleary et al 2003(Cleary et al , 2004, and xenografted to immunodeficient mice. To our knowledge, only one study (Kaneko et al 2003), in which neonatal pig ovarian tissues were xenografted, has proven that primordial oocytes can develop in the host mice and acquire fertilizing ability in vitro.…”

In Vitro and In Vivo Developmental Ability of Oocytes Derived from Porcine Primordial Follicles Xenografted into Nude Mice

“…Mouse oocytes that grow within ovarian tissue xenografted to nude rats acquire the ability to generate pups [3]. Moreover, ovarian tissues have been prepared from species phylogenetically distant from mice, including humans [4][5][6][7], dogs [8], monkeys [9], sheep [10], cows [11], pigs [12,13], tammar wallabies [14], and common wombats [15,16], and xenografted into immunodeficient mice. To date, there has only been one report [12] stating that primordial oocytes can develop in host mice and acquire fertilizing ability in vitro.…”