Tissue sites of alpha fetoprotein synthesis by the rat during pregnancy and hepatoma growth.

The tissue sites of alpha1 fetoprotein (AFT) synthesis by the rat during gestation and hepatoma growth were determined by specific incorporation of a radiolabeled amino acid precursor into AFP by tissue cultures in vitro. During gestation, AFP were produced by the yolk sac, the fetal liver, and in small amounts by the fetal gastrointestinal tract; there was no synthesis by maternal rat tissues. During growth of a transplantable hepatoma, only the hepatoma tissue synthesized AFP; the nontumor tissue of the host contained AFP but did not produce it.