Establishment and properties of human germ cell tumors in tissue culture.

Monolayer cultures of nine human testicular germ cell tumors have been attempted, and five have been established as proliferating long-term cultures. All five grew in suspension in nutrient agar, but three proliferated in monolayer culture only when in contact with stromal cells derived from the tumors. Two have been established as "pure" lines, and one of these has been cloned. All contain elevated levels of alkaline phosphatase, approximately one-half of which displays placental isoenzymic characteristics. Three tumor cultures formed differentiated tissues and synthesized significant quantities of beta-chorionic gonadotrophin or carcinoembryonic antigen for a brief period after a 5-month culture. These properties were subsequently lost and could not be reinduced.