Oxidative phosphorylation and the tricarboxylic acid cycle are essential for normal development of mouse ovarian follicles

BACKGROUND: Mouse ovarian follicles are typically grown in upright drops of culture medium. Recently we found that culture of follicles at the medium-gas interface in inverted drops markedly improved follicular development, possibly due to improved access of oxygen to the follicle. In this study, we examined the importance of aerobic energy metabolism for follicle development by culturing mouse follicles (198 6 16.5 initial microm diameter, mean 6 SD) in the presence of phosphorylation and tricarboxylic acid (TCA) cycle inhibitors. METHODS: All inhibitors were tested in the inverted system using 100 microl medium drops in 96-well plates; certain inhibitors were also tested in upright drops with or without an oil overlay. RESULTS: The oxidative phosphorylation inhibitor rotenone (0.1, 0.5 and 1 micromol/l) totally abolished follicle growth in the inverted system; cyanide (1 mmol/l) totally abolished growth in the upright with oil system but not in the inverted system (possibly due to loss of cyanide gas due to the absence of an oil overlay). The mitochondrial uncoupler 2,4-dinitrophenol (0.5 and 1 mmol/l) also abolished growth in the inverted system. The TCA cycle inhibitor monofluoroacetate (10 mmol/l), significantly inhibited growth in all three culture systems (P < 0.01) but malonate (10 mmol/l) had no effect. CONCLUSIONS: Aerobic metabolism and an adequate oxygen supply are essential for normal follicular development.