Follicular development in the chicken ovary is a critical biological process that influences egg-laying performance and directly impacts poultry production efficiency. However, elucidating the dynamic regulatory networks involving key genes and transcription factors (TFs) during follicular development remains a major challenge. In this study, we performed a comprehensive transcriptomic analysis across six follicular stages - small white follicles, large white follicles, small yellow follicles, and three hierarchical follicles - in high and low egg-laying hens. We identified a set of essential genes and pathways closely associated with egg-laying performance, including steroid hormone biosynthesis (e.g., CYP19A1, HSD3B1 ) and steroid biosynthesis (e.g., CEL, DHCR24, FDFT1 ), which play central roles in lipid metabolism, amino acid biosynthesis, and signal transduction. Pearson correlation analysis further enabled the construction of stage-specific TF regulatory networks, highlighting pivotal TFs such as FOXO1 and HOXA10 in follicular development. Additionally, two key genes - FABP3 and ENSGALG00000054605 were identified as significantly associated with reproductive traits, showing negative correlations with egg-laying rate and age at first egg, respectively. Their differential expression trends between high and low egg-laying hens suggest potential roles in regulating laying performance and sexual maturity. Importantly, based on transcriptome predictions, we conducted functional validation of BMPR1B , a core receptor in the TGF-beta signaling pathway identified as a major regulatory hub during follicle hierarchy formation. In vitro experiments demonstrated that BMPR1B promotes granulosa-cell proliferation, confirming its essential role in follicle maturation. Collectively, this study provides new insights into the molecular regulation of chicken follicular development by integrating multi-stage transcriptomics with functional validation. The findings offer valuable molecular markers - including BMPR1B, FABP3 , and ENSGALG00000054605 and potential targets for genetic improvement in poultry breeding, while also contributing to broader understanding of vertebrate reproductive biology.
Bai et al. (2026) studied this question.