In recent years, in vitro fertilization (IVF) technologies have advanced significantly and are now widely utilized. To date, more than 12 million babies have been born through IVF and related assisted reproductive technologies in humans. In livestock production, the number of embryos produced in vitro has surpassed those generated in vivo. These technologies are applicable across a range of species and have successfully resulted in the birth of offspring.

Most oocytes used for embryo production, such as in IVF, are obtained from antral follicles, which are mature and close to ovulation. However, the majority of oocytes in the ovaries reside in early-stage (immature) follicles, which are generally not used due to their limited developmental maturity and the challenges of maturing them outside the body. Technologies designed to promote the growth of these immature oocytes in vitro are known as in vitro growth (IVG). While promising results have been achieved in mice—including the birth of offspring from IVG and from oocytes derived via pluripotent stem cells—no successful IVG-based offspring have been reported from primordial follicles in other species. Even when using standard IVF protocols with oocytes from antral follicles, challenges remain, such as reduced developmental competence, low survival rates after cryopreservation, and complications like large offspring syndrome.

This Methods Collection aims to highlight and disseminate strategies for the effective utilization of ovarian oocytes across various species. It will emphasize methodologies such as oocyte and follicle collection, hormonal treatments, preservation techniques for oocytes and embryos, in vitro activation of primordial follicles, IVG, in vitro maturation (IVM), IVF, embryo culture, and in vitro gametogenesis from pluripotent stem cells.