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Combined effects of individual culture and atmospheric oxygen on preimplantation mouse embryos in vitro

Reproductive BioMedicine Online, Volume 33, Issue 5, November 2016, Pages 537–549

Highlights

  • Atmospheric oxygen and individual culture are standard embryo culture conditions, the effect of combining them is investigated here.
  • Cleavage timings, hatching rates and blastocyst cell numbers were reduced by either individual culture or atmospheric oxygen.
  • The combination of individual culture and atmospheric oxygen was more detrimental than either treatment alone.

Abstract

Embryos are routinely cultured individually, although this can reduce blastocyst development. Culture in atmospheric (20%) oxygen is also common, despite multiple detrimental effects on embryos. Although frequently occurring together, the consequences of this combination are unknown. Mouse embryos were cultured individually or grouped, under physiological (5%) or atmospheric (20%) oxygen. Embryos were assessed by time-lapse and blastocyst cell allocation. Compared with the control group (5% oxygen group culture), 5-cell cleavage (t5) was delayed in 5% oxygen individual culture and 20% oxygen group culture (59.91 ± 0.23, 60.70 ± 0.29, 63.06 ± 0.32 h post-HCG respectively, P < 0.05). Embryos in 20% oxygen individual culture were delayed earlier (3-cell cleavage), and at t5 cleaved later than embryos in other treatments (66.01 ± 0.40 h, P < 0.001), this delay persisting to blastocyst hatching. Compared with controls, hatching rate and cells per blastocyst were reduced in 5% oxygen single culture and 20% oxygen group culture (134.1 ± 3.4, 104.5 ± 3.2, 73.4 ± 2.2 cells, P < 0.001), and were further reduced in 20% oxygen individual culture (57.0 ± 2.8 cells, P < 0.001), as was percentage inner cell mass. These data indicate combining individual culture and 20% oxygen is detrimental to embryo development.

Keywords: group culture, IVF, oxidative stress, paracrine factors, single culture, time-lapse.

Footnotes

School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia

* Corresponding authors.