Experimental Endometrial Embolism in the Rabbit

The fate of autologous endometrial tissue introduced into the venous circulation was studied in 11 rabbits in the “resting” stage, “in heat,” post-partum and also in pregnancy. The operation consisted of laparatomy, with removal of about 1 cm. of a cornu, curettage of this portion, suspension of the scrapings in 3 cc. of homologous blood serum at room temperature, and immediate injection into the rabbit's ear vein. Histologic study of the tissues was made 30 sec, 12 hr., 24 hr., 48 hr., 1 week, 1 month, 69 days, 79 days, 109 days, and 130 days, after operation, the animals except for those which died of “embolic shock” 30 seconds after the injection, remaining in good health the entire period of their survival. The bulk of the cellular material was apparently filtered out in the lung arterioles and capillaries, no adventitious cells being found in the heart, spleen, kidneys or liver. Embolic cells, apparently viable could be recognized one week after injection but none could be identified after that time. Stromal cells possibly survive longer than epithelium. Fibrin is deposited about the cell emboli, their cytoplasm gradually disappears, the nuclei become pyknotic and break up, the embolus becoming converted into a hyaline mass in the smaller vessels and organized in the larger arterioles. Complete absorption or autolysis results in clearing of the pulmonary vessels of the autologous cell masses with no suggestion of formation of new endometrial tissue. These results are in agreement with the distribution of the characteristic lesions in cases of human ectopic endometriosis. While Sampson has found a venous dissemination of endometrial tissue within the human uterus and possibly in the groin, no instance of metastasis of non-neoplastic endometrial emboli has yet been observed above the diaphragm.