Early ovaries were isolated from embryos obtained from pregnant females at E13.5. The mesonephros was removed before the purification of germ and somatic cells. PGCs and somatic cells were purified using a paramagnetic technology according to Brieño-Enriquez et al. 2015. Briefly, groups of about 80 gonads were incubated in 0.25% trypsin-EDTA during 15 minutes at 37ºC, washed followed by incubation with PGC-specific antibodies (anti-CD15) bound to paramagnetic-microbeads. Finally, PGCs were isolated from somatic stromal cells by a magnetic column (miniMAcs) and stained both separated fractions with the naphtol AS-MX/ FAST-RED (Sigma-Aldrich) (PGC specific) to determine the level of enrichment of cell populations. In all cases, the enrichment of the PGCs was 93-96%. Similarly, the purity of somatic cells was over 90% in all samples. RNA was extracted using minipreps (Directzol DNA/RNA Miniprep de Zymo Research) following standar guidelines. The quality and quantity of RNA was using Bioanalyzer 2100 (Agilent Technologies). Always best quality samples were prioritized and no samples under 8 RIN were used for sequencing. Sequencing library was constructed from more than 1ug  of total RNA by BGI sequencing service