Fig. 1.

Granulosa cells (GCs) were collected from the antral follicles (3–5 mm in diameter) and cultured for 1 day to separate surviving GCs attached to the culture dish. On day 1, the surviving GCs were retrieved from the share and subsequently cultured under 5% CO₂ in air. On day 2, GCs with 70–80% confluence were subsequently incubated under atmospheric conditions of 5% CO₂ in air for 2 days, or under 5% O₂, 5% CO₂, and 90% N₂ for 24 h.