Generation of rat offspring from ovarian oocytes by xenotransplantation.

The idea of utilizing unused oocytes present in the ovaries has been tested in various ways to produce offspring. However, only a limited number of studies succeeded in offspring generation. They include transplantation of ovaries into autologous or allogeneic animals, and acquisition of pups from oocytes obtained by transplanting mouse ovaries into immunodeficient rats.

Production of marmoset eggs and embryos from xenotransplanted ovary tissues.

The common marmoset (Callithrix jacchus) has attracted attention as a valuable primate model for the analysis of human diseases. Despite the potential for primate genetic modification, however, its widespread lab usage has been limited due to the requirement for a large number of eggs. To make up for traditional oocyte retrieval methods such as hormone administration and surgical techniques, we carried out an alternative approach by utilizing ovarian tissue from deceased marmosets that had been disposed of.

Survivability and subsequent development of vitrified early-stage mouse embryos after warming at different temperatures.

Cryopreservation of embryos is a useful method for stably preserving various strains for a long time, and the cryopreserved embryos can be used at any time by simple warming. However, the viability of cryopreserved embryos, particularly vitrification at an early stage, is low compared to that of fresh embryos. As the warming process during vitrification is known to affect the survivability and subsequent development of embryos, the present study aimed to examine the viability and subsequent development of vitrified early-stage mouse embryos after warming at different temperatures.

Totipotency of mouse zygotes extends to single blastomeres of embryos at the four-cell stage.

In multicellular organisms, oocytes and sperm undergo fusion during fertilization and the resulting zygote gives rise to a new individual. The ability of zygotes to produce a fully formed individual from a single cell when placed in a supportive environment is known as totipotency. Given that totipotent cells are the source of all multicellular organisms, a better understanding of totipotency may have a wide-ranging impact on biology.

Tolerance to vitrification of rat embryos at various developmental stages.

Numerous genetically engineered rat strains have been produced via genome editing. Although freezing of embryos is helpful for the production and storage of these valuable strains, the tolerance to freezing of embryos varies at each developmental stage of the embryo. This study examined the tolerance to freezing of rat embryos at various developmental stages, particularly at the pronuclear stage.

In vitro maturation of immature rat oocytes under simple culture conditions and subsequent developmental ability.

Rat oocytes can be produced artificially by superovulation. Because some strains show low sensitivity to superovulation treatment, in vitro maturation is an alternative method to produce numerous matured oocytes. Furthermore, establishment of an in vitro maturation system with simple culture conditions is cost effective and leads to easy handling of oocytes.

Efficient collection and cryopreservation of embryos in F344 strain inbred rats.

In rats, it is now possible to produce genetically engineered strains, not only as transgenic animals but also using gene knockout techniques. Reproductive technologies have been used as indispensable tools to produce and maintain these novel valuable strains. Although studies for collecting and cryopreserving embryos have been reported using outbred rats, efficient methods have not been established in inbred strains.

Effect of androstenedione on the growth and meiotic competence of bovine oocytes from early antral follicles.

Medium that contains 17β-estradiol has been reported to support in vitro growth of bovine oocytes, isolated from early antral follicles, until the final stage. The aim of this study was to determine the effects of androstenedione in medium on such growing bovine oocytes. Oocyte-granulosa cell complexes were collected from early antral follicles and cultured for 14 days in medium supplemented with 17β-estradiol (0, 10 and 100 ng/ml) or androstenedione (0, 10 and 100 ng/ml).

Histological and biological assessment of vitrified ovarian follicles from large animals.

Mammalian ovaries contain mixed populations of follicles at different developmental stages. A combination of vitrification and growth culture of ovarian follicles could provide the desired number of mature eggs from a preserved small amount of ovarian tissues. Secondary and primordial follicles from porcine and bovine ovaries were vitrified in solutions containing ethylene glycol, dimethyl sulfoxide and different concentrations of sucrose, and assessed via histological examination, viability staining, xenografting to immunodeficient mice, and in vitro culturing.

FOXO3 knockdown accelerates development of bovine primordial follicles.

The objective of the present study was to elucidate the involvement of FOXO3 in the activation of bovine primordial follicles. In immunohistochemistry, FOXO3 was detected in all of the oocytes in primordial and primary follicles. The FOXO3 decreased after treatment with FOXO3 small interfering RNAs (siRNAs).

Bovine oocytes in secondary follicles grow in medium containing bovine plasma after vitrification.

There has been no culture system that supports the growth of bovine oocytes for more than 2 weeks. In the present study, bovine secondary follicles were cultured for 4 weeks, and the effects of supplemented protein components and FSH in the culture medium on the growth of the oocytes were examined. The effect of vitrification of secondary follicles on the subsequent oocyte growth was also examined.