The research group first targeted cynomolgus monkeys as a model organism for primates, including humans, and aimed to establish a culture technique for inducing follicles from ovary-derived cells of monkey fetuses. Cells (approximately 8 cells) collected from an 5-week-old fetal ovary were aggregated in a test tube (reconstituted ovary). However, in the suspension culture method, follicles were successfully induced by long-term culture for 12 weeks.

　Therefore, when we performed this culture method on ovarian-derived cells of an 8-week pregnant human fetus, which corresponds to an 11-week-old monkey fetus, follicle formation was observed in human reconstructed ovaries after a 14-week culture period. Admitted.As a result of the analysis, it was confirmed that these follicles underwent the same process of differentiation into oocytes as in the living body, leading to folliculogenesis even in an in vitro culture environment.In addition, the resulting oocytes had a gene expression state similar to that of oocytes present in adult ovaries.

　As a result, we succeeded in developing the world's first in vitro culture method for differentiating oogonia derived from the ovaries of human and monkey fetuses into oocytes and producing follicles.In addition, analysis of human and monkey oocytes obtained by this new culture method revealed a mechanism of oocyte development that is common to humans and monkeys and exists only in primates.

　The results of this research are expected to promote the understanding of the developmental mechanism of human female germ cells, and the development of reproductive medicine, such as elucidation of the etiology and development of treatments for germ cell-related diseases such as infertility.

Paper information:[The EMBO Journal] Ex vivo reconstitution of fetal oocyte development in humans and cynomolgus monkeys