Human endometrium transplanted into nude mice. Histologic effects of various steroid hormones.

In a histologic study of human endometrium transplanted into nude mice, eutopic endometrium from each of 8 women was transplanted subcutaneously to 4 nude mice, 1 of which was treated with polyestradiol phosphate, 1 with MPA, 1 with danazol, and 1 of which was left untreated as a control. Grafts were removed after varying intervals of up to 57 days. Residual histologically evaluable endometrial tissue was found in 32 of the 96 grafts (33%). None of the extirpated grafts had the same histologic pattern as the eutopic endometrium. Besides confirming that human endometrium can be transplanted into nude mice, our findings suggest that grafts react histologically in the same way as eutopic human endometrium to hormone treatment. The specific stroma seems to be crucial to a graft's capacity to respond to hormonal stimuli, and its replacement by fibrous tissue was accompanied by glandular epithelial changes very similar to those seen in human endometriotic lesions.