Eight-Cell Parthenotes Originated From In Vitro Grown Sheep Preantral Follicles

Abstract

We investigated the effect of the leukemia inhibitory factor (LIF) alone or in association with follicle-stimulating hormone (FSH) on the in vitro growth and antrum formation of sheep preantral follicles. To evaluate oocyte quality, parthenogenetic activation of the oocytes recovered from in vitro grown preantral follicles was performed. Preantral follicles >110 μm in diameter were isolated and cultured for 18 days in basic medium either alone (control) or supplemented with LIF (10 or 50 ng/mL) in the absence or presence of FSH. Every 6 days the follicular survival, growth, and antrum formation were evaluated. When compared to control (P < .05), antrum formation was increased in follicles cultured in the presence of LIF10 and FSH. At the end of the culture, the oocytes underwent in vitro maturation (IVM); their viability and chromatin configuration were assessed. Although IVM was not affect by the treatments (P > .05), the numerically highest maturation rates (29.63%) were obtained when follicles were cultured in 50 ng/mL LIF (LIF50). Therefore, their oocytes were submitted to parthenogenetic activation; from which 58.3% of the mature oocytes resulted in 8-cell stage parthenotes. In conclusion, although LIF10 + FSH increases antrum formation when compared to a nonsupplemented medium (minimum essential medium), oocytes from sheep preantral follicles are capable of growing and maturing in vitro independent of LIF addition to the medium, which resulted in the formation of 8-cell parthenotes.

Vitrified sheep isolated secondary follicles are able to grow and form antrum after a short period of in vitro culture

“…Our results are promising, and could be related to a rich culture medium used, supplemented with LIF and KL, among other additives. According to previous experiments, these substances have a positive effect on antrum formation and stimulate granulosa and theca cell proliferation (Luz et al 2012(Luz et al , 2013. Additionally, these molecules can enhance embryo production from in vitro-grown oocytes obtained from non-vitrified preantral follicles (Luz et al 2013).…”

In vitro culture of bovine preantral follicles: a review

“…However, besides the differences among species, in vitro follicle growth success depends on initial oocyte size, as well as follicle categories used. In regard to large animals, the production of embryos from buffalo [13], sheep [14, 15], goats [16], and monkeys [17] has been obtained only from large advanced secondary follicles. However, in mice, embryos and live offspring have been produced using developmentally competent oocytes obtained after growth entirely in vitro starting with primordial follicles [18, 19].…”

Ewe Ovarian Tissue Vitrification: A Model for the Study of Fertility Preservation in Women

“…The success of this technique has been acquired in the mouse model with the achievement of healthy offspring (Xu et al, 2006). Promising results have also been shown in other animals such as sheep (Luz et al, 2012;Luz et al, 2013) and non-human primates (Zelinski et al, 2008;Xu et al, 2009b), but further studies are required in order to achieve increased mature oocytes for embryo production.…”