Primordial germ cells are embryonic precursors of gametes and have enormous importance in the fields of developmental and conservation biology and aquaculture. Researching these cells meant development of applied science and science from a basic point of view. Primordial germ cells offer an insight into mechanisms of cell migration and proliferation during early embryonic development. One of the main objectives in preserving genetic material of endangered species is xenotransplantation. This means transplantation of endangered fish primordial germ cells into wide-spread recipients. Cryopreservation is the other objective in preservation of endangered genetic material. With development of basic knowledge on model fish species - zebrafish and medaka, development of method such as xenotransplantation and cryopreservation has been introduced in commercially more interesting species (e.g. Salmonidae).