The Natural History of Spontaneously Occurred Endometriosis in Cynomolgus Monkeys by Monthly Follow-Up Laparoscopy for Two Years

Hayashi K, Kaori Hayashi, Misako Nakayama, Chizuru Iwatani, Iwatani C, Tsuchiya H, Hideaki Tsuchiya, Nakamura S, Shinichiro Nakamura, Kosuke Nonoguchi, Nonoguchi K, Yasushi Itoh, Itoh Y, Shunichiro Tsuji, Hirohito Ishigaki, Ishigaki H, Mori T, Takahide Mori, Takashi Murakami, Murakami T, Kazumasa Ogasawara, Ogasawara K
The Tohoku Journal of Experimental Medicine · 2020 · vol. 251(4) , pp. 241–253 · doi:10.1620/tjem.251.241 · PMID:32713879 · W3044817079
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⚙ AI-generated summary by gemini-2.5-flash-lite, 2026-06-28 ⓘ

Monthly laparoscopies over two years revealed that spontaneously occurring endometriosis in cynomolgus monkeys progresses from the vesicouterine pouch, with new lesions appearing in all individuals and variable progression rates observed.

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⚙ AI-generated deep summary by claude@2026-07, 2026-07-09 · read from full text ⓘ

This study investigated the natural history of spontaneously occurring endometriosis in 11 female cynomolgus monkeys using monthly laparoscopic procedures over a two-year period, with mapping of endometriotic lesions and adhesions. At baseline, lesions were found exclusively in the vesicouterine pouch in 45.4% of monkeys and, over time, spread to the Douglas’ pouch; small de novo lesions appeared in all monkeys, while some small lesions disappeared in 18.2%. Endometriosis developed in all animals, with variable progression speeds that the authors attribute to differences in retrograde menstruation and potential genetic factors. Limitations include the small sample size and reliance on an animal model for quantifying spatiotemporal development. This paper is centrally about endometriosis — it characterizes the spontaneous spatiotemporal progression of endometriosis in a primate model, directly informing comparative understanding relevant to endometriosis (and not specifically adenomyosis).

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Abstract

Endometriosis, a disease in which endometrial tissue proliferates outside the uterus, is a progressive disease that affects women in reproductive age. It causes abdominal pain and infertility that severely affects the quality of life in young women. The mechanism of the onset and development of endometriosis has not been fully elucidated because of the complex mechanism involved in the disease. Nonhuman primates have been used to study the pathogenesis of spontaneous endometriosis because of their gynecological and anatomical similarities to humans. To reveal the natural history of endometriosis in cynomolgus monkeys, we selected 11 female cynomolgus monkeys with spontaneous endometriosis and performed monthly laparoscopies, mapping endometriotic lesions and adhesions up to two years. At the initial laparoscopy, endometriotic lesions were exclusively found in the vesicouterine pouch in 45.4% (5/11) of the monkeys and spread to the Douglas' pouch over time. Appearance of small de novo lesions and disappearance of some of the small lesions were observed in 100% (11/11) and 18.2% (2/11) of the monkeys, respectively. Endometriosis developed in all monkeys, and the speed of progression varied greatly among individuals that could be attributed to the degree or frequency of retrograde menstruation and genetic factors; these findings support the similarities between humans and monkeys, thus verifying the value of this nonhuman primate model. Finding reliable quantification markers and unravelling the underlying factors in correlation with the spatiotemporal development of the disease using a nonhuman primate model would be useful for the better management of endometriosis in humans.
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Keywords

cynomolgus monkey, endometriosis, laparoscopy, natural history of endometriosis, spontaneous endometriosis 2020 Volume 251 Issue 4 Pages 241-253 Details

Abstract

Endometriosis, a disease in which endometrial tissue proliferates outside the uterus, is a progressive disease that affects women in reproductive age. It causes abdominal pain and infertility that severely affects the quality of life in young women. The mechanism of the onset and development of endometriosis has not been fully elucidated because of the complex mechanism involved in the disease. Nonhuman primates have been used to study the pathogenesis of spontaneous endometriosis because of their gynecological and anatomical similarities to humans. To reveal the natural history of endometriosis in cynomolgus monkeys, we selected 11 female cynomolgus monkeys with spontaneous endometriosis and performed monthly laparoscopies, mapping endometriotic lesions and adhesions up to two years. At the initial laparoscopy, endometriotic lesions were exclusively found in the vesicouterine pouch in 45.4% (5/11) of the monkeys and spread to the Douglas’ pouch over time. Appearance of small de novo lesions and disappearance of some of the small lesions were observed in 100% (11/11) and 18.2% (2/11) of the monkeys, respectively. Endometriosis developed in all monkeys, and the speed of progression varied greatly among individuals that could be attributed to the degree or frequency of retrograde menstruation and genetic factors; these findings support the similarities between humans and monkeys, thus verifying the value of this nonhuman primate model. Finding reliable quantification markers and unravelling the underlying factors in correlation with the spatiotemporal development of the disease using a nonhuman primate model would be useful for the better management of endometriosis in humans. © 2020 Tohoku University Medical Press This article is licensed under a Creative Commons [Attribution-NonCommercial-NoDerivatives 4.0 International] license. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC-BY-NC-ND 4.0). Anyone may download, reuse, copy, reprint, or distribute the article without modifications or adaptations for non-profit purposes if they cite the original authors and source properly. https://creativecommons.org/licenses/by-nc-nd/4.0/ Favorites & Alerts Recently viewed articles - About this Journal The Tohoku Journal of Experimental Medicine (TJEM) was founded in 1920 by professors of Tohoku Imperial University, Medical School. The TJEM has been published continuously, except for the year of 1946 just after the World War II. The TJEM is open to original articles in all branches of medical sciences. The TJEM also covers the fields of disaster-prevention science, including earthquake archeology. - Submitted manuscripts will be screened for plagiarism with Similarity Check (https://www.crossref.org/services/similarity-check/). Announcements from publisher - Subscriptions Inland subscriptions should be sent to Tohoku University Medical Press, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, JAPAN. Subscriptions from abroad should be addressed to MARUZEN CO., LTD., EXPORT DEPARTMENT, Postal address: P.O.Box 75, Shinagawa, Tokyo 140-8799, JAPAN. e-mail: [email protected]

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Condition tags

endometriosisinfertility

MeSH descriptors

Endometriosis Laparoscopy Animals Body Weight Disease Progression Endometriosis Female Follow-Up Studies Macaca fascicularis Menstrual Cycle

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