We identified DMXL2 from RNA-sequencing data as a gene preferentially expressed in differentiating-ovaries in the goat species. In order to determine its role during ovarian morphogenesis, we investigated functional studies in mice. Dmxl2 invalidation (KO) is lethal within the few hours following birth. The analysis of its expression in several tissues let us show that the heart, olfactory mucosa and brain expressed Dmxl2 during development. Our results further suggest that the lethality may be due to an alteration of the synaptic transmission. Besides, both male and female gonads express Dmxl2. Notably in the ovary, its expression increases few days before follicle formation. We show that DMXL2 protein is dynamically expressed in germ cells and granulosa cells; DMXL2 is strongly detected in the oocytes whereas its expression in the granulosa cells fluctuates depending on the stage of folliculogenesis. To study Dmxl2 implication during follicle formation, and to bypass the issue of lethality at birth, we performed allograft of KO ovaries on nude recipient mice. KO grafts show an alteration in follicle formation, followed by ovarian dysgenesis. To conclude, our work shows that Dmxl2 is involved in follicle formation in mice, and makes it a new candidate to explain some cases of premature ovarian failure. The conditional knock-out of Dmxl2 in germ cells or in granulosa cells is in progress in the laboratory (please refer to Clara Gobé’s poster) and will permit to precise its specific role in each cell types.