STUDIES OF HYPERTHYROIDISM

Abstract

Experimental hyperthyroidism in urodele larvae (Amblystoma) and anuran larvae (Rana, Bufo, and Hyla) is accompanied by definite changes in bile color. The normal pale green or pale yellow-green color of the full gall bladder changes progressively after thyroid administration to brighter green, emerald green, and finally very dark green. In several hundred observations no exceptions were noted. Biliverdin (and its derivatives) is elaborated from hemoglobin. Thyroid administration increases the rate of erythrocyte destruction, and thus the output of bile pigment. Other minor factors are mentioned which may modify the color of the bile. Erythrocyte destruction occurs largely by enucleation, cytoplasmic segmentation, and fragmentation, and is probably widespread. Many fragments and senile red cells collect in the liver. During later stages of thyroid treatment the macro-phages become conspicuously active and are especially abundant in the liver, gut, and gills. In addition to the hemoglobin eliminated after transformation into bile pigment, some is transported by macrophages through the gut lining, and to a less extent through the involuting gill epithelium, and thus eliminated from the body.