FOXO3 overexpression delays primordial follicle activation in chickens

In chickens, overexpressing the transcription factor FOXO3 delays primordial follicle activation and maintains ovarian dormancy. Researchers created germline chimeric chickens carrying FOXO3-overexpressing primordial germ cells using a targeted germ cell ablation system. These modified germ cells showed reduced proliferation but retained normal migration and germline identity. Quantitative staging at 3, 4, 7, and 21 days post-hatch revealed that ovaries with elevated FOXO3 maintained a higher proportion of dormant primordial follicles and fewer growing follicles than controls. By day 21, dormant follicles displayed sustained nuclear or perinuclear FOXO3 localization. Overexpression also decreased apoptosis at 3 days post-hatch and blocked the activation of PI3K and AKT signaling at 4 days post-hatch.