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Reduced oxygen concentration improves the developmental competence of mouse oocytes following in vitro maturation
Author(s) -
Preis Kimberly A.,
Seidel George E.,
Gardner David K.
Publication year - 2007
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.20655
Subject(s) - oocyte , blastocyst , biology , oxygen tension , equine chorionic gonadotropin , embryo , in vitro maturation , andrology , embryogenesis , in vivo , embryo culture , human chorionic gonadotropin , endocrinology , medicine , oxygen , ovulation , chemistry , microbiology and biotechnology , hormone , genetics , organic chemistry
Reduced atmospheric oxygen concentration is beneficial to embryo development; however, optimal oxygen concentration for oocyte maturation remains undetermined. Likewise, there is no consensus of appropriate medium supplementation during maturation. The objective of this study was to determine whether oxygen tension (20% or 5% O 2 ) and epidermal growth factor (EGF) affect oocyte metabolism and subsequent embryo development. Cumulus‐oocyte complexes (COCs) were collected from 28‐day‐old equine chorionic gonadotropin (eCG) primed or unprimed F1 (C57BL/6xCBA) mice. COCs were matured in defined medium in one of four groups: 20% O 2 , 20% O 2 + EGF, 5% O 2 , 5% O 2 + EGF. In vivo matured COCs were also collected for analysis. COCs from unprimed mice, matured in 5% O 2 ± EGF or 20% O 2 + EGF had higher metabolic rates than COCs matured in 20% O 2 ( P < 0.05). COCs from primed mice had higher metabolic rates when matured in the presence of EGF, regardless of oxygen tension ( P < 0.01). Oxygen uptake and mitochondrial membrane potential were higher for in vivo matured oocytes and oocytes matured under 5% O 2 compared to oocytes matured under 20% O 2 ( P < 0.05). Blastocyst formation was not different between maturation groups (primed or unprimed); however, embryo cell numbers were 20–45% significantly higher when COCs were matured at 5% O 2 ( P < 0.05). Results suggest that oocytes matured in physiological concentrations of oxygen have improved development and metabolic activity, more closely resembling in vivo maturation. These findings have implications for oocyte maturation in both clinical and research laboratories. Mol. Reprod. Dev. 74: 893–903, 2007. © 2006 Wiley‐Liss, Inc.