Change of Tumor Specificity After Serial Passage on the Chick Chorioallantoic Membrane. ∗

Summary

1. The DBA mouse tumor was modified to grow subcutaneously in the hitherto resistant C57BL/6 and MA mouse strains. 2. The modification of histocompatibility of the tumor occurred after 2 serial passages on the C-A membrane. Compatibility with the 2 strains, the C57BL/6 and MA, appeared simultaneously while the C3H mice remained resistant. 3. After 6 serial passages in the new host strains, cross-inoculations between DBA/1, C57BL/6, and MA mice proved that the tumor had lost all specificity with respect to subcutaneous inoculation in the 3 strains.