Presumptive zygotes were vortexed for 2 min to separate
cumulus cells, washed three times in HM and twice
in the culture medium before putting them in the culture
droplets. Culture medium consisted of modified synthetic
oviductal fluid (mSOF) [28] containing 6 g/L BSA. The
mSOF was freshly prepared every week and adjusted to
285 mOsm and pH 7.2 to 7.3. Droplets of 50 L mSOF
were prepared in four-well dishes under mineral oil and
equilibrated for 2 h before the addition of 35 to 40 zygotes
per drop; culture was carried out at 39 °C, 5% CO2, 5%
O2 and 90% N2. Medium was renewed on Days 3 and 6
post IVF.