In Vitro Culture of Avian Primordial Germ Cells: Established Methods and Future Directions.

Primordial germ cells (PGCs) are the unipotent precursors of sperm and ova, responsible for transmitting hereditary information across generations. Their ability to be isolated and cultured in vitro has opened new horizons for avian biotechnology, species conservation, and fundamental developmental research. In birds, the unique migratory pattern of PGCs-originating in the epiblast and traveling via the bloodstream to the gonads-enables their collection and manipulation during embryogenesis. Long-term in vitro culture systems have been successfully established in chickens, where defined media allow for stable proliferation and genetic modification. Applications include germline chimeras, generation of transgenic lines, recombinant protein production, and cryobanking of genetic resources. However, translating these advances to other species remains challenging due to interspecies variability in signaling requirements. Recent work in geese, ducks, quails, and zebra finches underscores the need for tailored media formulations and a better understanding of molecular regulation. This review summarizes established techniques, highlights key interspecies differences, and outlines future directions for the standardization and expansion of avian PGC culture systems to support conservation and biotechnology.