Relationship of of Low Temperatures to X-ray Injury of Hematopoietic Tissue of Tadpoles.

Abstract

The hematopoietic cells of tadpoles occur in the caudal portion of the kidneys and undergo extensive mitotic division. They are destroyed by hard X-rays with a dosage of 500 r, leaving very few remaining after the lapse of 7 days. 196 tadpoles of Rana catesbiana were used in these expts. A study of cell destruction in tadpoles refrigerated at 0[degree] to 5.5[degree]C showed that these low temps. preserve all but a very small percent during the 24 hrs. of refrigeration. The ratio of destruction in the refrigerated compared with that at normal temps. (averaging 18.9[degree]C) ranged from 1:6 to 1:33. In one series of 58, tadpoles refrigerated for 4 days showed extremely little cell destruction, while those removed at the end of 2 days and maintained for 1 day or 2 days at normal temp. showed a very great amt. of destruction. Refrigeration before and during X-ray treatment did not give results appreciably different from those produced by refrigeration after irradiation. Thus, refrigeration prevents the degeneration of X-rayed hematopoietic cells but does not prevent the primary injury that leads to their degeneration at normal temps.