Establishment and characterization of a continuous in vitro line from a rat choriocarcinoma.

A continuous in vitro cell line of rat choriocarcinoma has been established. It is composed of pure trophoblast cells which multiply and differentiate. The morphology of the cells is very similar to normal rat cytotrophoblasts and giant cells. The cultured cells contain cytokeratin, alkaline phosphatase and express the receptors for Bandeira simplificifolia Agglutinin-I (BSA-I). They are hormonally active as demonstrated by the presence of lactogen and progesterone in the supernatant of the culture. The injected cells develop into choriocarcinoma in syngeneic as well as allogeneic rats. The morphological, biological and immunohistochemical features of these tumors are identical to those described in the transplantable neoplasm from which the in vitro line was established. The presence of Y chromosome in cultured cells proves the paternal origin of the primary tumor developed from extra-embryonic membranes in fetectomized rat and makes this neoplasm similar to human post-gestation choriocarcinoma.