Germline Stem Cells Drive Ovary Regeneration in Zebrafish

Germline stem cells (GSCs) sustain gametogenesis during the organismal life cycle. Although evidence suggests that GSCs are consistently present in the zebrafish ovary and support oogenesis, whether GSCs are involved in zebrafish ovary regeneration is poorly understood. Here, we found that nanos2, a conserved vertebrate GSC marker, is required for maintaining GSCs in zebrafish. We applied genetic ablation and tissue resection techniques to delineate the function of GSCs in zebrafish ovary regeneration. After GSC ablation, ovaries fail to regenerate and are converted to sterile testes. Amputated ovarian tissues completely regenerate as a result of the proliferation of residual GSCs, but nanos2 mutant ovaries fail to regenerate after amputation due to a lack of GSCs. The repression of Wnt signaling leads to reduced numbers of GSCs and delayed ovary regeneration. Our results provide insight into the key role of GSCs in driving ovary regeneration.