Influence of the Estrus Cycle and the Decidual Reaction on Transplanted Intra-Uterine Tumors in Mice *

Only rarely has the physiologically and dinically important organ, the uterus, been employed as a site for the growth of transplantable tumors. Guyer and Claus3 made a study of the effects of the Flexner-Jobling carcinoma transplanted into the uterus upon the cytology of the pituitary of the rat. In this and in a more extended study by Mohs and Guyer,9 it was found that in rats the endometrium was highly resistant to the implantation of the carcinoma, unless the uterus responded to the implant with the development of decidual tissue. The experiments described in this paper were undertaken to study the growth and implantation of a rapidly growing and malignant sarcoma placed within the lumen of the mouse uterus during the various periods of the estrus cycle and during early pregnancy and pseudopregnancy. The reaction of the uterus to the presence of the tumor and the manner of the implantation of the tumor into the endometrium were studied both in the normally cyclic uterus and in the uterus sensitized to the decidual reaction. The implantation of the mammalian embryo into the uterine wall has been the subject of much study and investigation. Burckhard' and Melissinos8 were among the first to make detailed histological studies in the mouse of the attachment of the embryo to the uterus and the accompanying decidual reaction. Leo Loeb7 first demonstrated that the development of decidual cells could be induced in the sensitized stroma of the rodent uterus by a stimulus other than the embryo. Other investigators have since shown that besides the stimulus of a mechanical injury, discovered by Loeb, foreign bodies and electrical shocks will serve as stimuli for the production of decidual growths in the sensitized uterus. Parkes"0