Early-stage endometriosis: adhesion and growth of human menstrual endometrium in nude mice

Objective: To evaluate the implantation of menstrual endometrium and the ea rly stages of evolution of endometriotic lesions. Design: Experimental prospective study. Setting: An academic research environment. Animals: Ten nude mice. Intervention(s): A minilaparotomy was performed to place fresh human menstr ual endometrial samples in the peritoneal cavity. Removal of the transplant s was performed successively on days 1, 3, and 5 by laparotomy. Main Outcome Measure(s): Adhesion of endometrial fragments and early stages of endometrial lesions was morphologically and immunohistochemically studi ed. Result(s): As early as day 1, stromal cells were found to be attached to th e mesothelium. A progressive reorganization of epithelial and stromal cells into endometrial glands was observed, On day 5, cystic endometriotic lesio ns were characterized by more extensive proliferative activity in glandular cells and a higher VEGF score in stromal cells than that observed in previ ously removed transplants. Conclusion(s): Menstrual human endometrium is able to implant on intact mes othelium and to reorganize itself into structured glands and stroma under t he influence of unknown factors. We suggest that stromal and glandular cell s have two distinct roles: stromal cells are involved in the attachment pro cess and glandular cells in the growth of the endometriotic lesion. (C) 200 0 by American Society for Reproductive Medicine.