Aims
(1) To develop a culture system that imitates a normal physiological environment of primordial germ cells (PGCs). There are two types of PGCs in chicken: Circulating blood (cPGCs) and gonadal (gPGCs). The culture condition must support the proliferation of both cPGCs and gPGCs, without affecting their migratory properties and must be deprived of xenobiotic factors, and (2) to propose an easy-to-train, nonlabeling optical technique for the routine identification of live PGCs. To address the first aim, early chicken embryo's feeder cells were examined instead of using feeder cells from mammalian species. The KAv-1 medium at pH 8.0 with the addition of bFGF (basic fibroblast growth factor) was used instead of a conventional culture medium (pH approximately 7.2). Both cPGCs and gPGCs proliferated in vitro and retained their migratory ability after 2 weeks of culture. The cultivated cPGCs and gPGCs colonized the right and/or left gonads of the recipient male and female embryos. To address the second aim, we demonstrated a simple and rapid method to identify live PGCs as bright cells under darkfield illumination. The PGCs rich in lipid droplets in their cytoplasm highly contrasted with the co-cultured feeder layer and other cell populations in the culture.