DNA-SYNTHESIS IN THYMUS AND OTHER ORGANS DURING THYMUS INVOLUTION OF TUMOR BEARING RATS

The incorporation of 3H-thymidin into the thymus and into tumor and other organs of tumor bearing rats (solid Walker tumor) is compared to lear whether tumor growth correlates with the degree of involution in the thymus. Our studies showed that a relation existed between tumor growth and thymus since the speed of incorporation in the tumor decreased in spite of a constant pool of precursor in the blood and lymph. The decrease was correlated with the histologically visible involution of the thymus. Perhaps in this way components of DNA disappear from the thymus and may be reutilized by other organs. The second maximum of precursor found in the tumor and in the thymus needs further study. The increase of radioactivity in the serum and liver is probably due to the decreasing capacity of tumor and thymus to incorporate the precursor. © 1969 Springer-Verlag.