Retinoic Acid Directly Regulates the Initiation and Completion of Meiosis in Chicken Primordial Germ Cells

Retinoic acid(RA) plays a key role in regulating meiotic initiation in fetal germ cells;however,it is not clear how RA interacts with gonadal cells and whether RA possesses the ability to induce germ cells to complete meiosis.In this study,we utilized purified chicken primordial germ cells(PGCs) culture system to investigate the direct effects of RA on entry of PGCs into meiosis,while excluding any effects from gonadal somatic cells.Results showed that RA significantly upregulated the mRNA and protein expression levels of STRA8,SYCP3 and DMC1 in chicken PGCs,thereby inducing entry of PGC into meiosis.Meanwhile,we found that RA is able to induce PGC to undergo all stages of meiotic phage,eventually leading to haploid cell formation,which was determined by giemsa stain and FACS analysis.Furthermore,our work revealed that the sensitivities of male and female PGCs in response to RA are quite similar.In conclusion,RA directly induces PGC to initiate and complete meiosis to produce haploid cells,which do not need the involvement of gonadal somatic cells or other factors.This work provides a platform for clinical application of infertility,as well as mechanistic understanding of gametogenesis.