Fast Green- and Light Green-Induced Tumors: Induction, Morphology, and Effect on Host

Fibrosarcomas have been induced at the site of repeated subcutaneous injection of Fast Green FCF, and Light Green SF, yellowish, in a very high percentage of female Fischer rats. The first tumors appeared during the 7th month of injections. No tumors appeared in control rats given analogous injections of distilled water, nor in those receiving a single injection of a 3 percent solution of either dye or of distilled water. The tumors appeared somewhat earlier in the Fast Green-treated rats, especially those started on 6 percent dye. Only minor morphological differences were noted between tumors induced by the two dyes. The microscopic structure of the tumors varied from areas with spindle cells and considerable collagen to highly cellular areas with no appreciable collagen. Some of the induced tumors and some of the transplanted tumors were locally invasive, and some metastasized to the lungs. The fibrosarcomas produced were freely transplantable into animals of both sexes in the rat strain of origin. Four representative tumor lines have been maintained for approximately 20 months by subcutaneous and intramuscular transplantation, without loss of viability. An interesting effect on the adrenal glands and gonads, resembling the changes seen in hypervolemia, has been observed in some rats bearing transplants of the two Light Green-induced lines still being maintained. Hypertrophy and marked hyperemia of the adrenals was seen in both sexes. The enlarged ovaries contained many hemorrhagic corpora lutea, while the seminiferous tubules of the testes were atrophic. Both Fast Green and Light Green were apparently decolorized, and hence possibly bound, by centrifugally isolated mitochondria and nuclei plus cellular debris of normal rat liver.