Abstract
In view of the accepted value of total embryo emulsion as on immunizing agent against propagable tumors first demonstrated by Schöne (Munch. Med. Woch., 1906, LIII, 2517) and later used successfully by many other investigators, the following notes on the influence of special embryonic tissues and of placenta on established rat sarcoma seem of sufficient interest to be reported.
The tumor used in these experiments was a sarcoma kindly supplied the laboratory by Dr. Loeb. During the period covered by the investigations it showed the following biological characteristics:
It was readily inoculated by direct subcutaneous transplantation of small intact fragments, giving by this method successful transplants in 93.2 per cent. of albino rats used in five separate operations. A palpable tumor usually developed in about six days, growing progressively and rapidly and having an average diameter of 30 mm. at the end of seven weeks. It usually invaded the skin and body wall only in the late stages of its growth. The average life of the animals after the inoculation was about ten weeks. No metastases were found on macroscopic post mortem examination. Retrogressions to complete disappearance occurred in six out of the fifty controls used in these experiments (12 per cent.). These retrogressions occurred only in the tumors which remained under 12 mm. in diameter. Recurrences after retrogression were not observed.
The animals used were albino rats about two thirds grown, males and females in about equal numbers.
The treatment was conducted with normal salt emulsions of the thyroid, the spleen and the liver of rat embryos prepared under aseptic precautions and preserved in the ice-chest under toluol, and also with an extract of placenta with the attached uterus washed free of blood and prepared in a similar manner.
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