FIGURE 1.

Deletion of Eif2s2 in premeiotic germ cells causes oocyte premature meiotic arrest and the failure of primordial follicle formation in mice. (A) Representative images of EIF2S2 staining in mouse ovaries at 18.5 days post‐coitum (dpc), 1,4 and 7 days postpartum (dpp). The enlarged views of the boxed area are shown on the bottom side. EIF2S2, green; DAPI, blue. Scale bar: 50 μM. (B) Immunostaining of EIF2S2 and DDX4 in Eif2s2 ^fl/fl and Eif2s2 ^cKO mouse ovaries. EIF2S2, green; DDX4, red; DAPI, blue. Scale bar: 50 μM. (C) Photographs of ovaries of 7 and14 dpp Eif2s2 ^fl/fl and Eif2s2 ^cKO mice. Scale bar: 200 μM. (D) Morphological comparison of ovaries of Eif2s2 ^fl/fl and Eif2s2 ^cKO mice. FOXL2, green; DDX4, red; DAPI, blue. The enlarged views of the boxed area are shown on the right side. Scale bar: 50 μM. (E) Number of oocytes in Eif2s2 ^fl/fl and Eif2s2 ^cKO ovaries at 1 dpp. n = 4. (F) Number of primordial follicles in Eif2s2 ^fl/fl and Eif2s2 ^cKO ovaries at 4 dpp. n = 4. (G) Representative images of SYCP3 (green, left panel) and GM130 (red, left panel), and YBX2 (green, right panel) and TRA98 (red, right panel) double staining in Eif2s2 ^fl/fl and Eif2s2 ^cKO ovaries at 3 dpp. The dashed circles indicate the nucleus of oocytes. The arrowhead indicates the SYCP3 cluster in dictyate oocytes. The arrow indicates the Balbiani body. (H) Percentage of oocytes reaching the dictyate stage, with Balbiani body, and with positive YBX signals in Eif2s2 ^fl/fl and Eif2s2 ^cKO ovaries at 4 dpp. n = 4. Bars represent the mean ± SD. A two‐sided Student's t‐test was performed to determine p values (*p < 0.05, **p < 0.01, and ***p < 0.001).