Abstract
Tissue changes following intravenous injections of thorium preparations have been well described by Kadrnka and Rossier, 1 Irwin, 2 Ravenna, 3 Shute and Davis, 4 and others, but a study of very early reactions seems to have been neglected. In our studies on the effect of colloidal thorium dioxide∗ upon blood and tissue cells of the rabbit, we have found that the early phase of reactions after a single intravenous injection is of great importance.
We injected 7 rabbits with 1 cc. per kg. and another 7 with a single dosage of 3 cc. per kg. They were killed 10, 15, 30 minutes, 1, 1½, 3, and 6 hours after the injection. Fresh blood smears were examined and various organs were removed and fixed in Zenker-formalin mixture. Histological sections were stained with acid fuchsin and methyl green. The green dye brings out the thorium in such a selective way that its identification inside as well as outside of the cell is greatly facilitated. In comparing the changes in the tissue of rabbits injected with 1 cc. with those of 3 cc, we found that the difference is only a matter of degree. In fact, rabbits treated with a large dosage proved to be more favorable for our purposes than cases injected with a small dosage. The following account is based upon observations in the 3 cc. dosage specimens.
Ten minutes after injection, thorium dioxide is readily identified in the spleen as a homogeneous mass of various sizes, distributed everywhere in the sinuses. Such a mass is not found in any other organ. In the specimen of 15 minutes after injection, it is found that thorium is present predominantly in the venous capillaries of the bone marrow and the liver. Here, the thorium appears to be in a free, finely granular state. The spleen at this time is full of thorium granules in the red pulp. As the latter structure is filled with slowly filtering blood, it is to be expected that more thorium particles are accumulated in the spleen than elsewhere. Due to this manner of accumulation the spleen shows a definite shadow in the roentgen-film. In the 30-minute specimen the spleen contains even more thorium granules than previously, while in the liver, bone marrow, suprarenal glands, lymph nodes, etc., no appreciable change in the amount of the thorium is found. This picture remains unchanged until 1 to 1½ hour after the injection.
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