Unsuccessful Induction of Endometriosis in Female Rhesus Macaques <i>(Macaca mulatta)</i>

Abstract

Background/Aims: The aim of this study was to induce endometriosis in female rhesus macaques (Macaca mulatta) for research purposes. Methods: Three female monkeys from 4 to 4.5 years of age underwent three consecutive attempts at endometriosis induction over an 8-month period: (i) the first attempt involved intravaginal sampling of endometrial tissue and transplantation into the intrapelvic cavity; (ii) the second entailed surgical removal of endometrium after hysterotomy and intra-abdominal placement, and (iii) the third used endometrial mucosa obtained by scraping the uterus after hysterectomy, placed in a surgical pouch created in the retrovesical space (Retzius). In each case, the pelvic cavity was closely inspected after 7, 9, and 6 weeks respectively for the presence of endometriotic lesions, and peritoneal biopsies were performed. Results: Neither macroscopic observation nor histological analysis revealed any endometriotic lesions. Conclusion: This failure to induce endometriosis in female rhesus macaques suggests that this species is not the most efficient experimental model among primates to investigate endometriosis development or treatment.

A protocol for creating endometriosis in rhesus macaques (Macaca mulatta)

“…This work validated a surgical protocol for creating endometriosis in rhesus macaques that recapitulates in part the outcome of retrograde menstruation. Earlier studies to develop a macaque model for induced endometriosis reported variable success 37,38 . Creating the disease in macaques via transcervical collection of menstrual endometrium is not feasible because the complex anatomy of the macaque cervix 42 .…”

“…Earlier studies to develop a macaque model for induced endometriosis reported variable success. 37,38 Creating the disease in macaques via transcervical collection of menstrual endometrium is not feasible because the complex anatomy of the macaque cervix. 42 Our uterine puncture technique provides a "surgically sterile" approach.…”

“…Macaques are the preferred NHP animal model for many research institutions and pharmaceutical industries. However, developing a rhesus macaque model for endometriosis has been ongoing for over 60 years with variable success 37,38 . Failure in creating the disease in naive monkeys via methods described for baboons appears to be methodological because the complex anatomy of the macaque cervix prevents reliable trans‐cervical catheterization.…”

“…However, developing a rhesus macaque model for endometriosis has been ongoing for over 60 years with variable success. 37,38 Failure in creating the disease in naive monkeys via methods described for baboons appears to be methodological because the complex anatomy of the macaque cervix prevents reliable trans-cervical catheterization. Moreover, maintaining a sterile transcervical collection of menstrual fragments is challenging in these species.…”