Germline organoids develop in vitro from embryonic Taeniopygia guttata (zebra finch) cultures.

Organoids are three-dimensional structures that develop in cultures of stem cells, and resemble multicellular organs. While performing long-term culture of Taeniopygia guttata (zebra finch) germline tissue, we observed the formation of germline organoids from cultures of both sexes. These macro-scale structures contain multiple cell types and retain Primordial Germ Cells (PGCs) and their descendant germ-cell lineages for two to four months of culture in vitro. We show that the PGC-specific germline-restricted chromosome (GRC) can be detected after three months of culture, and that the organoids exhibit DAZL- and DDX4-positive structures resembling germinal epithelia. Taken together our results open new possibilities for the study of key steps of avian reproductive development.