Functional Sex Reversal in Adult Gonochoristic Teleosts is Mediated by Ovarian Germline Stem Cell Plasticity and Somatic Cell Transdifferentiation

ABSTRACT

Sexual fate in vertebrates is generally considered developmentally fixed; however, teleost fishes exhibit remarkable flexibility in their reproductive systems. It remains unclear whether a fully differentiated gonochoristic vertebrate can undergo complete and functional sex reversal, or what molecular mechanisms could drive such reprogramming. Here, using the yellow drum ( Nibea albiflora ), a complete and functional female‐to‐male sex reversal is demonstrated in adulthood through three key mechanisms: (1) oocytes serve as guardians in the maintenance of ovarian fate, (2) ovarian germline stem cells retain spermatogenic potential and can produce sperm, and (3) ovarian somatic cells undergo complete transdifferentiation from granulosa/theca to Sertoli/Leydig lineages. This work provides the first evidence of functional female‐to‐male sex reversal in adult gonochoristic vertebrates, challenging existing paradigms about sexual fate fixation. Furthermore, these findings establish a novel experimental system for investigating vertebrate sexual plasticity and create a broadly representative model for sexual manipulation in teleost fishes.