Ovarian and follicular culture enables the production of fertile oocytes in C57BL/6 mice.

In vitro experiments have become a powerful alternative to in vivo approaches for analyzing gene functions and molecular mechanisms. However, successful in vitro oogenesis using the C57BL/6 strain-widely used as a standard mouse model in mammalian studies-has not yet been reported. In this study, we established a 30-day culture system combining ovarian and follicular culture, and successfully produced fully competent oocytes from neonatal C57BL/6N ovaries, which contain only non-growing oocytes prior to primordial follicle formation. A key contributing factor to this success was the supplementation of dibutyryl cyclic AMP, a membrane-permeable analogue of endogenous cyclic AMP, which promoted follicular growth. This culture system provides a valuable tool for investigating the mechanisms underlying oogenesis.