Hypoxia limits mouse follicle growth in vitro

Area of Science:

• Reproductive Biology
• Cellular Physiology
• In Vitro Culture Systems

Background:

• Ovarian follicle culture is crucial for understanding follicular function regulation.
• Preantral follicle development is essential for reproductive potential.

Purpose of the Study:

• To investigate the impact of oxygen concentration, oil overlay, serum type, and medium supplementation on preantral mouse follicle growth in vitro.
• To identify optimal conditions for in vitro follicle culture.

Main Methods:

• A spherical, non-attached follicle culture system was used to culture preantral mouse follicles.
• The effects of varying oxygen concentrations (5% vs. 20%), oil overlay, serum type, and supplementation with FSH, ITS, and ascorbic acid were assessed.
• Follicle diameter and VEGF secretion were measured.

Main Results:

• Significantly greater follicle growth (diameter) was observed in 20% oxygen compared to 5% oxygen (P < 0.01).
• Increased VEGF secretion in 5% oxygen suggests hypoxia.
• Oil overlay, ITS, and serum type did not significantly affect follicle growth (P > 0.05).
• Optimal growth to 380 μm in 6 days was achieved with 5% mouse serum, FSH, ascorbic acid, and 20% oxygen.

Conclusions:

• Adequate oxygenation is a critical factor for optimizing in vitro preantral mouse follicle growth.
• While supplemented media support growth, oxygen levels are paramount for efficient follicle development.
• Further optimization is needed as in vitro growth (380 μm) remains less than in vivo mature follicles (>500 μm).