Transplantation of normal and ectopic human endometrial tissue into athymic nude mice.

Implants or tiny circumscribed nodules of endometrial tissue were found in all female mice given intraperitoneal injections of fragments of human normal (proliferative and secretory) or ectopic (endometrioma) endometrium. Half of these animals received estrogen supplementation and the other half received none. The endometriosis tissue present in these animals at 28 or 56 days after inoculation consisted of glands and stroma with an infiltration of hemosiderin-laden macrophages. Glands in tissue transplants of animals given supplemental estrogen tended to be larger, and the secretory endometrium tended to revert to a proliferative pattern. Palpable nodules at the site of subcutaneous inoculations of proliferative endometrium became undetectable grossly and microscopically within 24 to 32 days, whereas endometrioma tissue remained detectable for up to 70 days and resembled the intraperitoneal tissue microscopically. This study demonstrates that human endometrial tissue can be successfully transplanted into the nude mouse and will retain its basic morphology.