FIGLA (folliculogenesis specific bHLH transcription factor) is a germline-specific transcription factor that plays a critical role in oocyte development and early folliculogenesis 1. The protein functions as a basic helix-loop-helix transcription factor that binds to E-box sequences in target gene promoters, regulating expression of multiple oocyte-specific genes including zona pellucida proteins (ZP1, ZP2, ZP3) essential for fertilization 1. FIGLA is essential for oocyte survival and primordial follicle formation, with deficiency leading to impaired meiotic progression, DNA damage, and oocyte apoptosis 2. The protein operates within a transcriptional network alongside LHX8 and SOHLH1, where these factors cross-regulate each other and cooperate through direct protein interactions to control oocyte growth and differentiation 2. FIGLA expression is detected throughout follicle development from primordial to secondary stages and in mature oocytes, with higher expression in adult versus pre-pubertal mice promoting secondary follicle growth 3. Mutations in FIGLA are associated with primary ovarian insufficiency (POI), contributing to approximately 1-2% of cases 45. Specific variants including p.(Arg83Cys) in the functional bHLH domain show strong association with idiopathic POF in clinical populations 6, highlighting FIGLA's importance in female reproductive health.