Maturation and Fertilization of Porcine Oocytes from Primordial Follicles by a Combination of Xenografting and In Vitro Culture1

Abstract

Our objective was to develop a method of endowing oocytes from porcine primordial follicles with full maturation and fertilizing ability as a model for ovarian xenografting of large mammals. Ovarian tissues from 20-day-old piglets, in which most of the follicles were primordial, were transplanted under the capsules of both kidneys of ovariectomized athymic mice. The host mice were treated with 5 IU of equine chorionic gonadotropin (eCG) for 10 days (eCG-10), 30 days (eCG-30), or 60 days (eCG-60) after detection of cornified epithelial cells in their vaginal smears. Cumulus-oocyte complexes, ovarian grafts, and blood samples were obtained 48 h after eCG treatment. Forty-five to 70 days after grafting, the host mice in all groups for the first time showed vaginal cornification, accompanied by the formation of a small number of antral follicles in the grafts. However, we recovered large numbers of full-sized oocytes only from mice in the eCG-60 group; the numbers of full-sized oocytes in the other groups were low. Peripheral levels of total inhibin were highest in the eCG-60 group; this supports our finding that the most enhanced growth of antral follicles occurred in this eCG-60 group. Of 573 oocytes obtained from the eCG-60 group, 98 (17%) were at the metaphase II stage after in vitro culture for maturation. Moreover, 55% of matured oocytes with the first polar body (n = 20) were fertilized in vitro. These results clearly demonstrate that fertilization of oocytes from porcine primordial follicles is achievable by a combination of xenografting and in vitro culture.

Knockdown of FOXO3 induces primordial oocyte activation in pigs

“…Recently, xenografting of ovarian tissues or follicles has begun to be used as a method to study oocyte growth and follicular development. Kaneko et al (2003) reported the development of primordial follicles to the antral stage at 45-75 days after xenografting ovarian tissues from 20-day-old pigs. The duration of follicular development in infant pigs in Growth of porcine primordial oocytes the present experiment is consistent with the result of Kaneko et al (2003).…”

“…Primordial follicles developed to the antral stage at 45-75 days after xenografting of the ovarian tissues from 20-day-old piglets (Kaneko et al 2003). On the other hand, the development of primordial follicles from cows (Senbon et al 2003) and prepubertal pigs (Moniruzzaman & Miyano 2007) was not initiated at 6-8 weeks after xenografting.…”

“…Gosden et al (1994) have developed a method of xenografting mammalian follicles to severe combined immune deficiency (SCID) mice as a model for investigating the early stages of follicular development. Follicular development in xenografts in immunodeficient mice has been reported in different species, including cats (Gosden et al 1994), sheep (Gosden et al 1994), pigs (Kaneko et al 2003), monkeys (Candy et al 1995), marsupials (Mattiske et al 2002), and humans (Oktay et al 1998).…”

Opportunities and challenges in applying genomics to the study of oogenesis and folliculogenesis in farm animals

“…Nevertheless, some studies have reported the growth from ovine and bovine preantral follicles to antral stage in precise culture conditions (Cecconi et al 1999, Itoh et al 2002. † Xenotransplantation of ovarian cortical slices from pig or cattle (Kaneko et al 2003, Senbon et al 2003 in immunodeficient SCID mice have also been attempted; some secondary follicles developed to the antral stage and the corresponding oocytes acquired the meiotic competence.…”

Des ovules en abondance ?

“…Le modèle interspécifique pourrait se révéler plus efficace si la folliculogenèse elle-même était assurée au sein d'un organisme animal. Ainsi, pour court-circuiter la difficulté d'obtenir la croissance folliculaire complète in vitro, il semble possible de réaliser la première étape (la plus longue) chez l'animal, comme cela a été montré pour le porc [26]: la biopsie ovarienne porcine contenant les follicules primordiaux est d'abord transplantée sous la capsule rénale d'une souris privée de thymus et d'ovaires. La croissance folliculaire étant stimulée (par des hormones gonadotropes), des follicules à antrum apparaissent, lesquels délivrent des ovocytes dont la fécondation a pu être obtenue après MIV et FIV.…”