Dynamic aspects of endometriosis in a mouse model through analysis of implantation and progression

The aim of this study was to use normal immunocompetent mice to set up a mo del for endometriosis which allowed to study the dynamic aspects involved i n initiation and progression of the disease. Thirty mice were surgically tr ansplanted with autologous endometrium and at 3 weeks showed evidence of en dometriosis. Diagnosis of endometriotic lesions was hystologically confimed . Visual inspection using a caliper revealed that, after an initial decreas e in size (from 33.44+/-2.33 mm(2) to 24.21+/-2.37 mm(2) (p<0.01)) detected at 3 weeks after transplantation, there was a significant increase of lesi on area from 21.30+/-3.15 mm(2) to 43.93+/-6.29 mm(2) (p<0.05) in the follo wing 3 weeks. When we compared these results to those obtained in mice whic h underwent bilateral annessiectomy, we observed that, when bilateral annes siectomy was performed simultaneously to endometrial transplantation, lesio n surfaces were similar between mice which were or were not subjected to bi lateral ovariectomy. On the other hand, when bilateral annessiectomy was pe rformed at second laparotomy and then evaluated after 4 weeks, differently from what observed in control mice, surface values decreased from 21.24+/-2 .29 mm(2) to 10.58+/-3.40 mm(2) (p<0.01). Finally, progression of lesions i n estrogen supplemented mice seems less evident than in control mice since only a slight but not significant increase in size (from 21.32+/-3.32 mm(2) to 26.18+/-6.98 mm(2), p=0.32) was detected. The results presented herein demonstrate that surgically induced endometrial implants in mice are dynami c lesions and that implantation and progression of endometriosis represent different stages in the ethiopathogenesis of the disease. Moreover, we show ed that progression, but not implantation, of ectopic endometrium is depend ent upon the functionally and structurally integrity of the ovaries. This i s a model of endometriosis established in normal immunocompetent mice, and, consequently, may represent a reliable tool for testing new immunological therapeutical approaches and studying the role of different genes using tra nsgenic mice.