Background: Endometriosis is a painful disorder in women where endometrium-like
tissue exists outside of the uterine cavity. Progress on new therapies for the disorder is dependent on
physiologically relevant models. Menstruation and development of spontaneous endometriosis only
occur in women and Old World nonhuman primates making nonhuman primates the most suitable
animals for study. Herein we review the use of nonhuman primates for studies on endometriosis.
Objective: To describe the use of nonhuman primates for studies on endometriosis.
Methods: We reviewed the literature comparing the use of primate models.
Results: In practice, three types of “primate” models exist; 1) studies on monkeys with spontaneous
endometriosis; 2) induction of endometriosis in disease-free animals; and, 3) the engraftment of
primate tissue into immunodeficient rodents. The absence of tests to identify animals with the wellcharacterized
disease greatly limits the viability of studies on spontaneous endometriosis in nonhuman
primates. Despite this limitation, studies of spontaneous endometriosis have elucidated risk
factors associated with the etiology and pathobiology of the disease. Induced endometriosis in the
baboon and macaque currently represents the prototypic and most promising primate model, producing
lesions that are phenotypically similar to endometriosis in women, with a well-controlled
onset, and predictable pathogenesis. The strength of using induced endometriosis models in
nonhuman primates lies in the ability to document the early disease process and the exact age of
lesions in the animals. However, nonhuman primates are expensive and in short supply. Xenografts
of primate tissue in immunodeficient mice also allow the study of the early disease process but
long-term studies are a compromise because of the immunodeficient nature of the host animals.
Studies of endometriosis in rhesus and cynomolgus macaques provides an additional benefit as
these are the preferred primate models for pharmacokinetic and pharmacodynamic studies in many
research institutes and the pharmaceutical industry.
Conclusion: Due to the physiological similarities among primates, preclinical studies of endometriosis
diagnostics and therapeutics conducted in nonhuman primate models are well-positioned to
lead to new clinical applications.