Human exhaled air can efficiently support in vitro maturation of porcine oocytes and subsequent early embryonic development.

Zubing Cao,Tengteng Xu,Di Gao,Xiaorong Zhang,Xu Tong,Yunsheng Li,Jianping Ding,Fugui Fang,Yiqing Wang,Yunhai Zhang

doi:10.21451/1984-3143-ar2017-0027

Abstract

Air phase is an indispensable environmental factor affecting oocyte maturation and early embryo development. Human exhaled air was previously proved to be a reliable and inexpensive atmosphere that sustains normal early development of mouse and bovine embryos. However, whether human exhaled air can support in vitro maturation (IVM) of porcine oocytes is not yet known. To evaluate the feasibility of maturing oocytes in human exhaled air, we examined oocyte morphology, BMP15 expression, nuclear and cytoplasmic maturation. We found that cumulus expansion status, expression levels of BMP15 important for cumulus expansion and the rate of first polar body emission were similar among human exhaled air, 5% O2 or 20% O2 in air after IVM of 44 h. Furthermore, the percentage of metaphase II (MII) oocytes showing normal cortical and sub-membranous localization of cortical granules and diffused mitochondrial distribution patterns is comparable among groups. The cleavage, blastocyst rate and total cell number were not apparently different for parthenogenetic activated and somatic cloned embryos derived from MII oocytes matured in three air phases, suggesting oocytes matured in human exhaled air obtain normal developmental competence. Taken together, human exhaled air can efficiently support in vitro maturation of porcine oocytes and subsequent early embryonic development.

Highlights

The faithful achievement of mammalian oocyte maturation is an essential prerequisite to carry out the robust preimplantation embryo development(Gilchrist and Thompson, 2007; Coticchio et al 2015)
Human exhaled air maintains normal nuclear maturation of porcine oocytes To explore the effects of different oxygen tensions on the nuclear maturation in vitro of immature porcine oocytes, we cultured cumulus-oocytes complexes (COCs) for 44 h under different air phase conditions involving human exhaled air, 5% O2 or 20%O2 in air
We found that cortical granules (CGs) in the majority of metaphase II (MII) oocytes matured in three air phases exhibited the distribution pattern of cortical and peripheral sub-membranous area (Fig.2 A)

Summary

Introduction

The faithful achievement of mammalian oocyte maturation is an essential prerequisite to carry out the robust preimplantation embryo development(Gilchrist and Thompson, 2007; Coticchio et al 2015). The external culture conditions of oocyte maturation in vitro are not yet optimal compared with naturally physiological environment in the reproductive tract (Fischer and Bavister, 1993; Roberts et al, 2002). This suboptimal culture environment may induce many detrimental roles in oocytes in vitro maturation and subsequent early embryonic development. Air phases commonly utilized for oocyte maturation in vitro are mainly separated into two categories involving 5% CO2,20% O2,75% N2 (high oxygen tension; Bavister, 1995) and 5% CO2,5% O2, 95% N2 (low oxygen tension)(Adam et al, 2004; Kang et al 2012). Internal culture environment including temperature, humidity and CO2 equilibrium are often perturbed due to frequent openings of the incubator door which could result in

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Conclusion