Gynecologic pathology in the rhesus monkey (Macaca mulatta). II. Findings in laboratory and free-ranging monkeys

Endometriosis and adenomyosis: Similarities and differences

Deep endometriosis and uterine adenomyosis are two frequently encountered conditions affecting approximately 200 million women worldwide. They are closely related, showing similar histological patterns and multiple common pathogenic features, and share the same symptoms. It is therefore not surprising that they are often thought to have a common developmental origin. Indeed, both deep endometriosis and adenomyosis appear to derive from estrogen-dependent overproliferation of endometrial tissue and its subsequent implantation in ectopic sites. Although the scientific community has shown increasing interest in these diseases over recent years, neither pathogenesis has yet been elucidated, so there are currently no efficient treatment options. Understanding the mechanisms underlying disease development, as well as discerning their relationship, are key to improving clinical management for millions of patients. The aims of this review are to summarize current knowledge on deep endometriosis and adenomyosis pathogeneses and discuss the possibility that these two entities are actually differential phenotypes of the same disease.

Unveiling the Pathogenesis of Adenomyosis through Animal Models

Background: Adenomyosis is a common gynecological disorder traditionally viewed as “elusive”. Several excellent review papers have been published fairly recently on its pathogenesis, and several theories have been proposed. However, the falsifiability, explanatory power, and predictivity of these theories are often overlooked. Since adenomyosis can occur spontaneously in rodents and many other species, the animal models may help us unveil the pathogenesis of adenomyosis. This review critically tallies experimentally induced models published so far, with a particular focus on their relevance to epidemiological findings, their possible mechanisms of action, and their explanatory and predictive power. Methods: PubMed was exhaustively searched using the phrase “adenomyosis and animal model”, “adenomyosis and experimental model”, “adenomyosis and mouse”, and “adenomyosis and rat”, and the resultant papers were retrieved, carefully read, and the resultant information distilled. All the retrieved papers were then reviewed in a narrative manner. Results: Among all published animal models of adenomyosis, the mouse model of adenomyosis induced by endometrial–myometrial interface disruption (EMID) seems to satisfy the requirements of falsifiability and has the predictive capability and also Hill’s causality criteria. Other theories only partially satisfy Hill’s criteria of causality. In particular, animal models of adenomyosis induced by hyperestrogenism, hyperprolactinemia, or long-term exposure to progestogens without much epidemiological documentation and adenomyosis is usually not the exclusive uterine pathology consequent to those induction procedures. Regardless, uterine disruption appears to be a necessary but not sufficient condition for causing adenomyosis. Conclusions: EMID is, however, unlikely the sole cause for adenomyosis. Future studies, including animal studies, are warranted to understand how and why in utero and/or prenatal exposure to elevated levels of estrogen or estrogenic compounds increases the risk of developing adenomyosis in adulthood, to elucidate whether prolactin plays any role in its pathogenesis, and to identify sufficient condition(s) that cause adenomyosis.

Naturally Occurring Endocrine Disorders in Non-Human Primates: A Comprehensive Review

Simple Summary

Nonhuman primates (NHP) can become ill due to a variety of diseases and disorders, yet endocrine disorders remain underreported. Therefore, an exhaustive literature search on this subject via widely used academic search systems, peer-reviewed publications, proceedings, and newsletters was performed. Selected major endocrine entities will be described emphasizing clinical signs, morphologic features, concomitant diseases, as well as available treatment options. In most cases, no clinical signs were noted and on gross pathology, the endocrine organs were unremarkable. The diagnosis was frequently made as incidental findings after standard histological examination. Although the findings were frequently incidental many have the potential to impact studies. This review explains that there is no standard procedure for diagnosing, monitoring, or treating endocrine disorders in NHP. More research is needed to evaluate these procedures and establish risk factors.

Abstract

Literature concerning veterinary medicine of non-human primates is continuously updated, yet endocrine disorders remain underreported. While case or survey reports of individual endocrinopathies are available, a comprehensive review is not. An exhaustive literature search on this subject via widely used academic search systems, (e.g., Google Scholar, PubMed, BioOne complete and Web of Science), and peer-reviewed publications, proceedings, and newsletters was performed. Selected major endocrine entities will be described with emphasis on clinical signs, morphologic appearances, concomitant diseases, as well as available treatment options. Mostly, no clinical signs were noted and on gross pathology, the endocrine organs were unremarkable. An endocrine-related diagnosis was frequently made as an incidental finding after standard histopathological examination. During the review, the pancreas represented the most affected endocrine organ and diabetes mellitus represented the most clinically significant disorder. Currently, no standard procedure for diagnosing, monitoring, or treating endocrine disorders in non-human primates exists.

International Harmonization of Nomenclature and Diagnostic Criteria (INHAND): Non-proliferative and Proliferative Lesions of the Non-human Primate (M. fascicularis)

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions Project (www.toxpath.org/inhand.asp) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP) and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying microscopic lesions observed in most tissues and organs from the nonhuman primate used in nonclinical safety studies. Some of the lesions are illustrated by color photomicrographs. The standardized nomenclature presented in this document is also available electronically on the internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous lesions as well as lesions induced by exposure to test materials. Relevant infectious and parasitic lesions are included as well. A widely accepted and utilized international harmonization of nomenclature for lesions in laboratory animals will provide a common language among regulatory and scientific research organizations in different countries and increase and enrich international exchanges of information among toxicologists and pathologists.

Report of the National Cancer Institute and the Eunice Kennedy Shriver National Institute of Child Health and Human Development-sponsored workshop: gynecology and women's health-benign conditions and cancer

The Division of Cancer Prevention and the Division of Cancer Biology at the National Cancer Institute and the Gynecologic Health and Disease Branch in the National Institute of Child Health and Human Development organized a workshop in April 2019 to explore current insights into the progression of gynecologic cancers from benign conditions. Working groups were formed based on 3 gynecologic disease types: (1) Endometriosis or Endometrial Cancer and Endometrial-Associated Ovarian Cancer, (2) Uterine Fibroids (Leiomyoma) or Leiomyosarcoma, and (3) Adenomyosis or Adenocarcinoma. In this report, we highlight the key questions and current challenges that emerged from the working group discussions and present potential research opportunities that may advance our understanding of the progression of gynecologic benign conditions to cancer.

Animal Models of Adenomyosis

Adenomyosis is a nonmalignant uterine disorder in which endometrial tissue exists within and grows into the myometrium. Animal models have generated limited insight into the still-unclear pathogenesis of adenomyosis, provided a platform for preclinical screening of many drugs and compounds with potential as therapeutics, and elucidated mechanisms underlying the pain and fertility issues that occur in many women with the disease. Spontaneous adenomyosis has been studied in nonhuman primates, primarily in the form of case reports. Adenomyosis is routinely experimentally induced in mice through methods such as neonatal tamoxifen exposure, pituitary engraftment, and human tissue xenotransplantation. Several studies have also reported hormonal or environmental toxicant exposures that give rise to murine adenomyosis, and genetically engineered models have been created that recapitulate the human-like condition, most notably involving alteration of β-catenin expression. This review describes the animal models for adenomyosis and their contributions to our understanding of the factors underpinning the development of symptoms. Animal models represent a unique opportunity for understanding the molecular basis of adenomyosis and developing efficacious treatment options for affected women. Herein, we assess their different potentials and limitations with regard to identification of new therapeutic interventions and reflect on future directions for research and drug validation.

Primate model research for endometriosis

Endometriosis is defined as the existence of endometrial tissue outside the uterine cavity, and it includes a chronic, inflammatory reaction associated with female infertility and pelvic pain. Endometriosis occurs in 7 to 10% of women. Although it has been studied for more than 50 years, the pathogenesis and development of endometriosis are still poorly understood. There is no curative therapy for endometriosis, which often recurs after surgical or medical treatment. There is a consensus that the adverse current of menstrual blood plays a crucial role in the development of endometriosis. This places a major limitation on research using rodent models of endometriosis, although these are still widely employed, because rodents do not menstruate and endometriosis does not occur spontaneously in these animals. In fact, menstruation and spontaneous endometriosis only occur in women and some non-human primates, making models that employ non-human primates the best animal models for research into the pathogenesis, pathophysiology, spontaneous onset, and treatment of endometriosis. This review assesses the effectiveness and potential of the non-human primate models of endometriosis. It also describes the current findings and theories on the pathogenesis of endometriosis that have been obtained by research using non-human primates.

Bilateral hydronephrosis secondary to endometriosis managed by endoscopic ureteral stent placement in a captive Guinea baboon (Papio papio)

Spontaneous endometriosis is an estrogen-dependent, progressive and painful disease that affects a variety of nonhuman primates, including several species of baboons (Papio sp.). This case documents multimodal management of severe endometriosis in a captive female baboon within a zoological institution. An 18-yr-old, intact female Guinea baboon (Papio papio) was found to have an enlarged uterus. Fifteen months post ovariohysterctomy, scarring associated with endometrial tissue resulted in ureteral strictures, bilateral hydronephrosis, and azotemia. Cystoscopic placement of bilateral ureteral stents with fluoroscopy was performed and resulted in short-term clinical improvement. The animal's condition declined and euthanasia was elected 4 mo after ureteral stent placement. Severe endometriosis with secondary inflammation resulting in bilateral hydroureter and hydronephrosis, as well as concurrent cystitis, ureteritis, and pyelonephritis were confirmed at necropsy. Despite possible complications, ureteral stents can be considered a useful therapeutic option in patients with ureteral disease.

Expression of Siglec-11 by human and chimpanzee ovarian stromal cells, with uniquely human ligands: implications for human ovarian physiology and pathology

Siglecs (Sialic acid-binding Immunoglobulin Superfamily Lectins) are cell surface signaling receptors of the I-type lectin group that recognize sialic acid-bearing glycans. CD33-related-Siglecs are a subset with expression primarily in cells of hematopoietic origin and functional relevance to immune reactions. Earlier we reported a human-specific gene conversion event that markedly changed the coding region for the extracellular domain of Siglec-11, associated with human-specific expression in microglia (Hayakawa T, Angata T, Lewis AL, Mikkelsen TS, Varki NM, Varki A. 2005. A human-specific gene in microglia. Science. 309:1693). Analyzing human gene microarrays to define new patterns of expression, we observed high levels of SIGLEC11 transcript in the ovary and adrenal cortex. Thus, we examined human and chimpanzee tissues using a well-characterized anti-Siglec-11 mouse monoclonal antibody. Although adrenal expression was variable and confined to infiltrating macrophages in capillaries, ovarian expression of Siglec-11 in both humans and chimpanzees was on fibroblasts, the first example of Siglec expression on mesenchyme-derived stromal cells. Cytokines from such ovarian stromal fibroblasts play important roles in follicle development and ovulation. Stable transfection of SIGLEC11 into a primary human ovarian stromal fibroblast cell line altered the secretion of growth-regulated oncogene α, interleukin (IL)-10, IL-7, transforming growth factor β1 and tumor necrosis factor-α, cytokines involved in ovarian physiology. Probing for Siglec-11 ligands revealed distinct and strong mast cell expression in human ovaries, contrasting to diffuse stromal ligands in chimpanzee ovaries. Interestingly, there was a trend of increased Siglec-11 expression in post-menopausal ovaries compared with pre-menopausal ones. Siglec-11 expression was also found on human ovarian stromal tumors and in polycystic ovarian syndrome, a human-specific disease. These results indicate potential roles for Siglec-11 in ovarian physiology and human evolution.

Morphologic and Immunohistochemical Features of the Cynomolgus Macaque Cervix

Female macaques serve as an important model for the study of reproductive diseases in women. Here we summarize characteristics of the macaque cervix, with a particular emphasis on the cynomolgus macaque. Key anatomic features include a stratified squamous exocervix, squamocolumnar junction and transformation zone, and glandular endocervix with prominent colliculi. Endocervical eversion occurs with onset of ovarian cycling and regresses to varying degrees based on age, hormonal status, and individual conformation. The cervical epithelium in macaques is highly responsive to estrogens, which induce marked squamous epithelial maturation and glandular hypertrophy. Progestogen effects include further induction of endocervical secretory activity and release of viscous mucus, which functions in both mucosal immunity and fertility regulation. On immunohistochemistry, the squamous cervix shows strong expression of estrogen receptor α, the proliferation marker Ki67/MIB1, and cytokeratin 14, whereas endocervical epithelium strongly expresses estrogen and progesterone receptors and cytokeratins 18 and 19. These patterns of expression are altered in cervical intraepithelial neoplasia, which is a common spontaneous lesion of the macaque cervix associated with specific types of oncogenic papillomaviruses. This report highlights important similarities with human cervix that should be useful for future studies of genital infection, neoplasia, and immunity in the macaque model.

Competing Interests: This article was sponsored by Covance Inc. and Schering-Plough. The author did not declare any other competing interests.

The Macaque Endometrium, with Special Reference to the Cynomolgus Monkey (Macaca fascicularis)

The macaque endometrium undergoes dramatic morphologic and functional changes during the menstrual cycle that are nearly identical to those of the human endometrium. The sequential events that take place in the endometrium are mainly driven by the ovarian steroids and their respective receptors. To be able to interpret the changes and effects induced by mammalian or synthetic hormones and other compounds that could have influence on the hormonal status of the animal, a thorough knowledge of the anatomy, physiology, and histology of the cyclic hormone-mediated processes within the endometrium is indispensable. In this paper we give an overview of uterine growth and development, anatomy, basic histology, aging, spontaneous pathology, and the techniques to study the endometrium in-life. In addtion, a comprehensive description of the receptor-mediated, hormone-driven morphological changes during the menstrual cycle in the cynomolgus monkey (Macaca fascicularis) is given. Where possible, differences between the macaque and human endometria are discussed.

Competing Interests: This article was sponsored by Covance Inc. and Schering-Plough. Gerhard F. Weinbauer and Eberhard Buse are employed by Covance Inc. Eric Van Esch is employed by Schering-Plough. No other competing interests were declared.

Selected Background Findings and Interpretation of Common Lesions in the Female Reproductive System in Macaques

The authors describe a selection of normal findings and common naturally occurring lesions in the reproductive system of female macaques, including changes in the ovaries, uterus, cervix, vagina, and mammary glands. Normal features of immature ovaries, uteri, and mammary glands are described. Common non-neoplastic lesions in the ovaries include cortical mineralization, polyovular follicles, cysts, ovarian surface epithelial hyperplasia, and ectopic ovarian tissue. Ovarian neoplasms include granulosa cell tumors, teratomas, and ovarian surface epithelial tumors. Common non-neoplastic uterine findings include loss of features of normal cyclicity, abnormal bleeding, adenomyosis, endometriosis, epithelial plaques, and pregnancy-associated vascular remodeling. Hyperplastic and neoplastic lesions of the uterus include endometrial polyps, leiomyomas, and rarely endometrial hyperplasia and endometrial adenocarcinoma. Vaginitis is common. Cervical lesions include endocervical squamous metaplasia, polyps, and papillomavirus-associated lesions. Lesions in the mammary gland are most often proliferative and range from ductal hyperplasia to invasive carcinoma. Challenges to interpretation include the normal or pathologic absence of menstrual cyclicity and the potential misinterpretation of sporadic lesions, such as epithelial plaques or papillomavirus-associated lesions. Interpretation of normal and pathologic findings is best accomplished with knowledge of the life stage, reproductive history, and hormonal status of the animal.

Spontaneous adenomyosis in the chimpanzee (Pan troglodytes): a first report and review of the primate literature: Case Report

Adenomyosis is a non-neoplastic condition characterized by the presence of ectopic endometrium in the myometrium with hyperplasia of adjacent smooth muscle. Common symptoms in women include debilitating pelvic pain and abnormal uterine bleeding, and the condition has been paradoxically associated with both multiparity and subfertility. Adenomyosis spontaneously occurs in humans and some non-human primates, including the baboon and macaque, where it has been associated with primary infertility and the presence of endometriosis. No cases of adenomyosis have been previously reported in Pongidae such as gorilla, orangutan or chimpanzee. We here describe two cases of naturally occurring adenomyosis in the chimpanzee (Pan troglodytes) and briefly review the literature regarding the presence of adenomyosis in non-human primate species.

Characterization and experimental transmission of an oncogenic papillomavirus in female macaques

Cervical cancer is one of the leading causes of cancer mortality in women worldwide, yet few suitable animal models currently exist for study of this disease. Virtually all cases of cervical cancer in women are caused by specific types of genital human papillomavirus (HPV). In this study, we investigated naturally occurring genital PVs in female cynomolgus macaques (Macaca fascicularis) without breeding contact for at least 3.5 years. Exfoliated cervicovaginal cells from 19 of 54 animals tested positive for at least one PV. Seven different PVs were identified, including four novel genotypes and two genotypes (RhPV-d and RhPV-a) previously identified in rhesus macaques (Macaca mulatta). Four PV types were associated with cervical intraepithelial neoplasia (CIN), which resembled human CIN by endoscopy, cervical cytology, histology, and immunohistochemistry. The presence of CIN was highly associated with PV infection (P<0.0001). The most prevalent virus type was RhPV-d, which was identified in 60% of animals with CIN. An RhPV-d genome sequenced from a high-grade CIN lesion was found to be phylogenetically related to the highly oncogenic HPV16. Transfer of cervical cytobrush samples from donor animals naturally carrying RhPV-d resulted in new infections in 4 of 12 previously virus-free animals and abnormal cytology and histology in 1 of 4 infected animals after 18 weeks of infection. Experimental transmission was confirmed by E1/\E4 reverse transcription-PCR products and RhPV-d sequence identity with the donor variant. These findings identify key similarities between macaque and human oncogenic PVs which should prove useful in the study of viral persistence, carcinogenesis, and therapeutic development.

Experimental adenomyosis

Adenomyosis has been reported in a number of different animal species, whereas endometriosis appears limited to humans and non-human primates. This suggests a different aetiology of the two conditions. Adenomyosis develops spontaneously in certain strains of laboratory mice. Its incidence in mice can be markedly enhanced by systemic exposure to various hormonal agents, including prolactin, progesterone, synthetic progestins, certain oestrogenic agents, as well as tamoxifen and toremifene. The precise hormonal changes necessary remain unclear, although the evidence suggests that adenomyosis in this model is not due to a simple oestrogenic effect. Study of the pathological and molecular alterations in this model indicates that disturbances to the uterine stroma, blood vessels and myometrium are also important factors in the development of adenomyosis.

Safety and distribution of cellulose acetate 1,2-benzenedicarboxylate (CAP), a candidate anti-HIV microbicide in rhesus macaques

OBJECTIVES

To assess the safety and distribution of a cellulose acetate 1,2-benzenedicarboxylate (CAP) gel formulation in rhesus macaques as part of the development process for its use as a vaginally administered product in humans.

DESIGN

The similarities between the reproductive physiology, anatomy and vaginal microflora of human and non-human primates makes non-human primates a relevant animal model to assess the safety and distribution of candidate anti-HIV microbicides.

METHODS

CAP gel was instilled once or once daily for 4 days into the vaginal vault of rhesus macaques. Colposcopy and magnetic resonance imaging were performed to detect adverse effects and spread of CAP, respectively. Additionally, vaginal pH and composition of the vaginal micorflora in macaques before, during and after CAP instillations were determined, and vaginal biopsies obtained following repeated CAP exposures were examined to further document its safety.

RESULTS

CAP is safe for repeated use and exhibits a favorable distribution profile, showing no evidence of penetration into cells that line the vaginal epithelium. Further, the presence of CAP has no adverse effect on vaginal pH or the composition of the vaginal microflora, and does not induce vaginal epithelial thinning or inflammation.

CONCLUSIONS

CAP gel shows minimal toxicity in vivo, supporting its use as a candidate vaginal microbicide in humans.

Neoplasms of the reproductive tract: the role of hormone exposure

Cancers of the reproductive system are a major source of morbidity and mortality among women worldwide. Because the uterus, ovaries, and cervix are hormonally responsive tissues, exposure to endogenous or exogenous sex steroids can profoundly affect the carcinogenic process. Animal models developed to date provide valuable but imperfect systems in which to study neoplasms of the reproductive tract. Nonhuman primate models share the unique primate-specific endometrial physiology of humans, but rarely develop neoplasms of the reproductive tract. Therefore a surrogate marker approach is required for the study of hormonally induced cancer risk in primates. Rodents provide practical models in which tumorigenesis can be assayed in a short time and, with appropriate interpretation, can be used for assessment of risk, prevention, and therapeutic strategies. In addition to the spontaneous strain-dependent incidence of female reproductive cancers, the classical chemical and hormonal carcinogenesis models, and the use of xenograft approaches, novel genetically modified animals provide unique insights into relevant molecular mechanisms. Caveats in the use of rodent models include anatomical differences from the human reproductive tract, the greater possibility of different metabolic responses to hormonal agents than humans, strain variations in tumor type and hormonal responsiveness, and unexpected tumor phenotypes in genetically modified animals. Reported nonmammalian models are limited primarily to the study of ovarian carcinogenesis. Recent progress in the understanding of cervical carcinogenesis is encouraging. Unmet needs in this area of research include models of early events in ovarian carcinogenesis and strongly predictive models of endometrial cancer risk. Nonhuman primates remain indispensable for the study of some aspects of reproductive pathophysiology, but the best understanding of carcinogenesis in the reproductive tract requires a broad approach using complementary human, nonhuman primate, and nonprimate studies.

Endometrial hyperplasia, polyps, and adenomyosis associated with unopposed estrogen in rhesus monkeys (Macaca mulatta)

The purpose of this study was to evaluate the effects of estrogen and progesterone on the vaginal mucosa and their role in vaginal transmission of simian immunodeficiency virus. Incidentally, endometrial hyperplasia was observed in estrogen-treated monkeys at necropsy. Six adult female rhesus monkeys (Macaca mulatta) were ovariectomized and 120 days later received two subcutaneous implants, each containing 200 mg estradiol. The animals were sacrificed 17-27 months later and the uterus examined at necropsy. All the monkeys had simple endometrial hyperplasia, some with polyps or adenomyosis, at the time of necropsy. The severity of the changes correlated with the time between implantation and necropsy. The lesions were similar to endometrial hyperplasia caused by unopposed estrogen in women, but occurred over a time period that is suitable for experimental manipulation. Rhesus monkeys could be used as a model to test the safety of various combinations of sex steroids for the prevention of postmenopausal symptoms in women.

Record review of baboons with histologically confirmed endometriosis in a large established colony

Spontaneous endometriosis was diagnosed in 43 baboons over a 14-year period. Thirty-seven have died; five remain alive; one was sold and lost to follow-up. The average age at diagnosis was 17.2 years; 29 (67%) were between 12 and 21 years of age. Fifteen (35%) were diagnosed by biopsy and received surgical excision of the endometriotic tissue; four of these were identified during caesarian section, confirming one prior report of endometriosis in pregnant animals. Twenty-eight (65%) were diagnosed at or shortly preceding necropsy. When diagnosed by a palpable abdominal mass, there was a significantly greater likelihood the animal died or was killed as a result of complications of endometriosis. When diagnosis was at necropsy, there was a significantly greater likelihood that the animal died from causes unrelated to endometriosis. Early identification with surgical removal appears to provide a benefit for both survival and delivering offspring after diagnosis. In twenty-one baboons (49%), endometriosis affected multiple sites within the peritoneal cavity. In the remaining baboons, lesions were more localized. Ovarian involvement was seen in sixteen (37%) of these baboons. This paper is the first to describe significant ovarian involvement in baboons, previously considered a limitation of the usefulness of this species as an animal model. We also describe the first reported endometriosis seeding of an abdominal surgery scar in a baboon. Many of these baboons were middle aged, had few or no offspring, or had evidence of a long duration of uninterrupted menstrual cycles, consistent with risk factors for women. Endometriosis was an incidental finding in 17 (40%) of these baboons, consistent with previous reports of minimal endometriosis as a common asymptomatic finding in baboons and in women. Overall, endometriosis in baboons presents a spontaneously occurring animal model that shares important features with the disease in women and the rhesus macaque.

Clinical relevance of the baboon as a model for the study of endometriosis

OBJECTIVE

To review the value of the baboon as a model for the study of endometriosis.

DATA IDENTIFICATION AND SELECTION

Studies performed at the Institute of Primate Research in Nairobi, Kenya (1990-1994), and published in peer-reviewed journals.

RESULT(S)

Spontaneous endometriosis was found in about 25% of the baboons, and its prevalence increased with the duration of captivity. The laparoscopic appearance, pelvic localization, and microscopic aspects of the disease were similar to endometriosis in women. Microscopic endometriosis in macroscopically normal peritoneum was rare. Sampson's hypothesis (i.e., retrograde menstruation causes endometriosis) was supported by the increased incidence of retrograde menstruation in baboons with spontaneous endometriosis, the observation that cervical occlusion could cause retrograde menstruation and endometriosis, and the finding that intrapelvic injection of menstrual endometrium caused experimental moderate to severe endometriosis similar to the spontaneous disease. During follow-up of more than 2 years, endometriosis in baboons appeared to be a progressive disease, with active remodeling between several types of lesions. Progression was stimulated by high-dose immunosuppression. Fertility was normal in baboons with minimal disease but was reduced in baboons with mild, moderate, or severe endometriosis, possibly related to an increased incidence and recurrence of the luteinized unruptured follicle syndrome.

CONCLUSION(S)

The baboon is a good model for the study of endometriosis.

Spontaneous external endometriosis in a De Brazza's monkey

A spontaneous case of external endometriosis in a 22-year-old female De Brazza's monkey is described. During diagnostic laparotomy, peritoneal adhesions of the uterus to the urinary bladder, ovaries and abdominal wall were seen. A surgical biopsy of soft tissue attached to the ventral surface of the uterus was examined histologically and consisted of endometrial glands and stroma. These findings were compatible with a diagnosis of endometriosis.

Molecular cloning and characterization of the DNA of two papillomaviruses from monkeys

Benign and malignant lesions from monkeys were analyzed for the presence of papillomavirus (PV) DNA. By hybridization with different PV DNA probes under conditions of lowered stringency, two tumors were found to contain PV-specific DNA sequences: (1) a cutaneous papilloma from a Colobus monkey; and, (2) a lymph node metastasis of a squamous cell carcinoma of the penis from a Rhesus monkey. Analysis of the DNA of the papilloma from the Colobus monkey indicated the presence of extrachromosomal DNA whereas analysis of DNA from the Rhesus tumor suggested the presence of integrated viral DNA. The physical size (7.8 and 8.1 kb), colinear alignment to HPV-5, and cross-hybridization with other PV types under low stringency indicate that the two genomic DNA clones represent new PV types that have been tentatively designated as Rhesus papillomavirus type 1 (RhPV 1) and Colobus guereza papillomavirus type 2 (CgPV 2). A putative viral-host DNA junction fragment was also isolated from the Rhesus genomic library. Nucleotide sequences very closely related to RhPV 1 were observed by in situ hybridization in a laryngeal carcinoma from the Colobus guereza monkey. This report communicates the finding of novel papillomaviruses associated with a benign cutaneous tumor and genital and laryngeal malignancies in non-human primates which may have significance as a putative system for the study of papillomavirus-induced genital and laryngeal malignancies in humans.

Endometriosis in rhesus monkeys

Endometriosis was present in five out of six Rhesus monkeys who had to be sacrificed because of disease in a colony of 90. The monkeys lost appetite and became constipated. The abdomen was distended and often a pelvic mass could be palpated. At autopsy, 300-500 ml of blood-stained fluid was found in the abdomen together with intestinal or pelvic endometriosis. The ethiology of endometriosis in Rhesus monkeys is unknown. The most probable explanation is intraabdominal implantation of endometrial tissue through retrograde menstruation. The lesion is rare in animals in free ranging colonies. It is not known whether this is due to a higher frequency of pregnancies in animals with free access to matings or to its consequences, i.e. more infrequent menstruations.

Dysplasia of the lower genital tract in the female monkey, Macaca fascicularis, the crab-eating macaque from Southeast Asia

Seventy-eight female reproductive tracts from mature Macaca fascicularis caught in the wild were examined histologically for evidence of dysplasia in immature (metaplastic) and native (mature) squamous epithelium of the cervix and vagina. This series contained equal numbers of experimental animals and control and/or breeding colony animals. Five of 39 experimental animals showed dysplasia, whereas six animals with definite and two with questionable dysplasia were found in 39 control and breeding colony animals. On the basis of the foregoing facts, it would appear that these dysplastic lesions were of spontaneous origin and of undetermined etiology. Therefore, those investigators who experiment upon the reproductive tract of this species of monkey should be wary of interpreting any given experiment as "causing" dysplasia. Monkeys of this same species, born and reared in our Primate Center, have been examined for comparable dysplastic lesions of the lower female genital tract. None was found thus far but the study is continuing.