Spontaneous neoplasms observed in cynomolgus monkeys (Macaca fascicularis) during a 15-year period

Bipedalism and the dawn of uterine fibroids

The high prevalence and burden of uterine fibroids in women raises questions about the origin of these benign growths. Here, we propose that fibroids should be understood in the context of human evolution, specifically the advent of bipedal locomotion in the hominin lineage. Over the ≥7 million years since our arboreal ancestors left their trees, skeletal adaptations ensued, affecting the pelvis, limbs, hands, and feet. By 3.2 million years ago, our ancestors were fully bipedal. A key evolutionary advantage of bipedalism was the freedom to use hands to carry and prepare food and create and use tools which, in turn, led to further evolutionary changes such as brain enlargement (encephalization), including a dramatic increase in the size of the neocortex. Pelvic realignment resulted in narrowing and transformation of the birth canal from a simple cylinder to a convoluted structure with misaligned pelvic inlet, mid-pelvis, and pelvic outlet planes. Neonatal head circumference has increased, greatly complicating parturition in early and modern humans, up to and including our own species. To overcome the so-called obstetric dilemma provoked by bipedal locomotion and encephalization, various compensatory adaptations have occurred affecting human neonatal development. These include adaptations limiting neonatal size, namely altricial birth (delivery of infants at an early neurodevelopmental stage, relative to other primates) and mid-gestation skeletal growth deceleration. Another key adaptation was hyperplasia of the myometrium, specifically the neomyometrium (the outer two-thirds of the myometrium, corresponding to 90% of the uterine musculature), allowing the uterus to more forcefully push the baby through the pelvis during a lengthy parturition. We propose that this hyperplasia of smooth muscle tissue set the stage for highly prevalent uterine fibroids. These fibroids are therefore a consequence of the obstetric dilemma and, ultimately, of the evolution of bipedalism in our hominin ancestors.

Subcutaneous leiomyosarcoma in a cynomolgus macaque (Macaca fascicularis)

Leiomyosarcoma, a malignant tumour originating from smooth muscle cells, has rarely been documented in non-human primates. In this case study, a 7-year-old female cynomolgus macaque (Macaca fascicularis) presented with a rapidly growing mass overlying the left elbow joint. Radiographs indicated the presence of a soft tissue neoplasm without any associated bone involvement. The mass was surgically resected. Histological and immunohistochemical analyses revealed spindle-shaped cells with eosinophilic cytoplasm that resembled smooth muscle cells, exhibiting positive immunoreactions for vimentin, desmin and smooth muscle actin and a negative reaction for pan-cytokeratin. This is the first reported case of subcutaneous leiomyosarcoma in a cynomolgus macaque and provides important insights into the incidence and characteristics of this condition in this species.

Multiple adenomas of the thyroid gland in an African green monkey (Chlorocebus aethiops)

Two cystadenomas and one solid adenoma of the thyroid gland in a 27-year-old female African green monkey (Chlorocebus aethiops) are described here. Histologically, the solid adenoma was classified as a well-defined solid follicular adenoma of microfollicular type. The solid adenoma was positive for thyroglobulin in immunohistochemistry staining, whereas the cystadenomas stained positive for both thyroglobulin and calcitonin. No evidence of excess hormone production related to the tumor presence was detected.

Selected Resources for Pathology Evaluation of Nonhuman Primates in Nonclinical Safety Assessment

Humans and nonhuman primates (NHPs) share numerous anatomical and physiological characteristics, thereby explaining the importance of NHPs as essential animal models for translational medicine and nonclinical toxicity testing. Researchers, toxicologic pathologists, toxicologists, and regulatory reviewers must be familiar with normal and abnormal NHP biological traits when designing, performing, and interpreting data sets from NHP studies. The current compilation presents a list of essential books, journal articles, and websites that provide context to safety assessment and research scientists working with NHP models. The resources used most frequently by the authors have been briefly annotated to permit readers to rapidly ascertain their applicability to particular research endeavors. The references are aimed primarily for toxicologic pathologists working with cynomolgus and rhesus macaques and common marmosets in efficacy and safety assessment studies.

Isolation of TCR genes with tumor-killing activity from tumor-infiltrating and circulating lymphocytes in a tumor rejection cynomolgus macaque model

To develop effective adoptive cell transfer therapy using T cell receptor (TCR)-engineered T cells, it is critical to isolate tumor-reactive TCRs that have potent anti-tumor activity. In humans, tumor-infiltrating lymphocytes (TILs) have been reported to contain CD8⁺PD-1⁺ T cells that express tumor-reactive TCRs. Characterization of tumor reactivity of TILs from non-human primate tumors could improve anti-tumor activity of TCR-engineered T cells in preclinical research. In this study, we sought to isolate TCR genes from CD8⁺PD-1⁺ T cells among TILs in a cynomolgus macaque model of tumor transplantation in which the tumors were infiltrated with CD8⁺ T cells and were eventually rejected. We analyzed the repertoire of TCRα and β pairs obtained from single CD8⁺PD-1⁺ T cells in TILs and circulating lymphocytes and identified multiple TCR pairs with high frequency, suggesting that T cells expressing these recurrent TCRs were clonally expanded in response to tumor cells. We further showed that the recurrent TCRs exhibited cytotoxic activity to tumor cells in vitro and potent anti-tumor activity in mice transplanted with tumor cells. These results imply that this tumor transplantation macaque model recapitulates key features of human TILs and can serve as a platform toward preclinical studies of non-human primate tumor models.

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.

Urogenital Lesions in Nonhuman Primates at 2 National Primate Research Centers

Given their genetic and anatomic similarities to humans, nonhuman primates (NHPs) may serve as animal models for urogenital diseases of humans. The purpose of this study was to examine the frequency of spontaneous urogenital lesions occurring over a 30-year period at the Yerkes and Southwest National Primate Research Centers and to compare and contrast lesions occurring in Old World versus New World primates. Lesions occurring in the chimpanzee (Pan troglodytes), baboon (Papio spp.), rhesus macaque (Macaca mulatta), cynomolgus macaque (Macaca fascicularis), pig-tailed macaque (Macaca nemestrina), sooty mangabey (Cercocebus atys), common marmoset (Callithrix jacchus), cotton-top tamarin (Sanguinus oedipus), and squirrel monkey (Saimiri sciureus) are discussed. The most common lesions of the kidney were medullary amyloidosis, renal cysts, renal tubular degeneration, glomerulonephritis or glomerulopathy, nephritis, nephrocalcinosis, pyelonephritis, and hydronephrosis. Specific causes of renal tubular disease included pigmentary nephrosis and tubular lipidosis. Renal tumors, including renal adenoma and carcinoma, lymphoma, and nephroblastoma, were infrequent diagnoses in all species. Endometriosis was the most frequently diagnosed lesion of the female genital tract. Of the animals examined in this study, it was most frequent in Old World primates. Leiomyoma was the most common uterine tumor. Granulosa cell tumor was the most frequently observed neoplasm of the ovaries, followed by teratoma. Of animals included in the study, most ovarian tumors occurred in baboons. Neoplasms of the male reproductive tract included interstitial cell tumor, seminoma, penile squamous cell carcinoma, penile papilloma, and histiocytoma. In New World monkeys, renal lesions were reported more frequently than genital lesions.

LESIONS OF THE FEMALE REPRODUCTIVE TRACT IN JAPANESE MACAQUE ( MACACA FUSCATA) FROM TWO CAPTIVE COLONIES

Reproductive lesions have been described in various nonhuman primate species, including rhesus macaques ( Macaca mulatta), cynomolgus macaques ( Macaca fascicularis), baboons ( Papio spp.), squirrel monkeys ( Saimiri sciureus), and chimpanzees ( Pan spp.); however, there are few publications describing reproductive disease and pathology in Japanese macaques ( Macaca fuscata). A retrospective evaluation of postmortem reports for two captive M. fuscata populations housed within zoos from 1982 through 2015 was completed, comparing reproductive diseases diagnosed by gross pathology and histopathology. Disease prevalence, organs affected, and median age at death between the two institutions was also compared. Fifteen female captive M. fuscata, ranging in age from 15 to 29 yr were identified with reproductive tract lesions, including endometriosis, endometritis, leiomyoma, leiomyosarcoma, and adenomyosis. No significant differences were identified in disease prevalence, organs affected, and median age of death between the two institutions. Endometriosis was the most common disease process identified and was found in 10 of the 15 cases (66.7%), followed by leiomyoma (4 of 15; 26.7%). In four cases (26.7%), severe endometriosis and secondary hemorrhage was indicated as the cause of death or the primary reason for humane euthanasia. These findings were compared with a separate population of Japanese macaques managed within a research facility in the United States, with a prevalence of endometriosis of 7.6%. This study discusses possible risk factors and potential treatment options for the management of endometriosis in captive M. fuscata.

Spontaneous pulmonary adenocarcinoma and subcutaneous cavernous hemangiomas arising in a squirrel monkey (Saimiri sciureus)

Benign and malignant pulmonary tumors have been reported in both Old World and New World monkeys but are uncommon. Hemangiomas are also rarely reported in nonhuman primates. Here we present a case of two primary neoplasms (a papillary adenocarcinoma of bronchioloalveolar origin and multiple cavernous subcutaneous hemangiomas) arising in an aged squirrel monkey (Saimiri sciureus).

MHC-identical and transgenic cynomolgus macaques for preclinical studies

Cynomolgus macaques are useful experimental animals that are physiologically and genetically close to humans. We have developed two kinds of experimental usage of cynomolgus macaque: transplantation and disease models. First, we identified certain major histocompatibility complex (MHC) haplotypes including homozygotes and heterozygotes in cynomolgus macaques native to the Philippines, because they have less polymorphism in the MHC than that in other origins such as Vietnam and Indonesia. As a preclinical model of the induced pluripotent stem cell (iPSC) stock project, we established iPSCs from various types of MHC homozygous macaques, which were transplanted into compatible MHC heterozygous macaques, the iPSC stock project was experimentally shown to be effective. Second, to obtain disease models of cynomolgus macaques for studies on regenerative medicine including cell therapies, we established two kinds of genetic technology to modify cynomolgus macaques: transgenic technology and gene editing technology using CRISPR-Cas9. We will establish disease models, such as Alzheimer's disease and progeria (Werner syndrome). In future, we will distribute the MHC-identical cynomolgus monkeys and genetically modified macaques to researchers, especially those engaging in regenerative medicine.

Spontaneous pulmonary adenosquamous carcinoma in a free-living black capuchin monkey (Sapajus nigritus)

Pulmonary neoplasia is rare among wild New World primates. We report the gross, microscopical, and immunohistochemical features of a primary multicentric pulmonary adenosquamous carcinoma in a free-living black capuchin monkey (Sapajus nigritus). Herein, the spectrum of pulmonary neoplasms in non-human primates is widened and briefly reviewed.

Transplantation of iPS-Derived Tumor Cells with a Homozygous MHC Haplotype Induces GRP94 Antibody Production in MHC-Matched Macaques

Immune surveillance is a critical component of the antitumor response in vivo, yet the specific components of the immune system involved in this regulatory response remain unclear. In this study, we demonstrate that autoantibodies can mitigate tumor growth in vitro and in vivo We generated two cancer cell lines, embryonal carcinoma and glioblastoma cell lines, from monkey-induced pluripotent stem cells (iPSC) carrying a homozygous haplotype of major histocompatibility complex (MHC, Mafa in Macaca fascicularis). To establish a monkey cancer model, we transplanted these cells into monkeys carrying the matched Mafa haplotype in one of the chromosomes. Neither Mafa-homozygous cancer cell line grew in monkeys carrying the matched Mafa haplotype heterozygously. We detected in the plasma of these monkeys an IgG autoantibody against GRP94, a heat shock protein. Injection of the plasma prevented growth of the tumor cells in immunodeficient mice, whereas plasma IgG depleted of GRP94 IgG exhibited reduced killing activity against cancer cells in vitro These results indicate that humoral immunity, including autoantibodies against GRP94, plays a role in cancer immune surveillance. Cancer Res; 77(21); 6001-10. ©2017 AACR.

The Impact of Age on the Female Reproductive System

Evaluation of the female reproductive system in a general toxicity setting can be challenging for the toxicologic pathologist due to the cyclic nature of the estrous and menstrual cycles, timing of puberty and reproductive senescence, and species differences. Age in particular can have a significant impact on the histologic appearance of the female reproductive system and create challenges when trying to distinguish test article-related findings from normal developmental or senescent changes. This review describes the key physiologic and histologic features of immaturity, the transition through puberty, sexual maturity, and reproductive senescence in the female reproductive system, with an emphasis on practical applications for the toxicologic pathologist, and includes recommendations for distinguishing and documenting these developmental periods. Rats and cynomolgus monkeys are used as examples throughout with correlations to clinically observed end points to better aid the toxicologic pathologist in understanding how age may impact study interpretation.

Use of ultrasound imaging for the diagnosis of abnormal uterine bleeding in the bonnet macaque ( Macaca radiata)

Ultrasound is a powerful, low-cost, non-invasive medical tool used by laboratory animal veterinarians for diagnostic imaging. Sonohysterography and transvaginal ultrasound are frequently used to assess uterine anomalies in women presenting with abnormal uterine bleeding (AUB). In the present study, we have evaluated the abdominal ultrasound of bonnet monkeys ( n = 8) showing spontaneous ovulatory ( n = 5) and anovulatory ( n = 3) AUB. The ovulatory ( n = 5) macaques showed cyclic AUB for 7-8 days. The anovulatory ( n = 3) macaques had irregular AUB with menstrual cycles of 40-45 days. The B-mode abdominal, colour Doppler and 3D ultrasound scans were performed during the proliferative phase of the menstrual cycle. Ultrasound examination revealed endometrial polyps in five macaques and endometrial hyperplasia in three animals. The width and length of endometrial polyps was around 0.5-1 cm (average 0.51 ± 0.23 cm × 0.96 ± 0.16 cm) with significant increase in endometrial thickness ( P < 0.0002). 3D ultrasound also showed a homogeneous mass in the uterine cavity and colour Doppler ultrasound showed increased vascularity in the endometrial polyps. Endometrial hyperplasia characteristically appeared as a thickened echogenic endometrium ( P < 0.0002). This study demonstrates the use of non-invasive ultrasound techniques in the diagnosis of AUB in macaques.

Advantages and Limitations of Commonly Used Nonhuman Primate Species in Research and Development of Biopharmaceuticals

Nonhuman primates (NHPs) have been used extensively during the past four decades for research and nonclinical development because they are close to humans in terms of genetics, anatomy, physiology, and immunology. They have been widely used in the development of infection models, leading to the generation of vaccines and drugs, as well as in the nonclinical pharmacologic and toxicologic assessment of biopharmaceuticals, especially in the fields of immunotherapy and oncology, despite the constant pressure to move to lower species. In many cases, NHPs are the only species that allows a correct risk assessment for humans. Nevertheless, limitations inherent to each species have to be considered before an investigation. This chapter shines some light on the respective interests and limitations of using cynomolgus monkeys, rhesus monkeys, and marmosets in medical research and nonclinical development, with a specific focus on reproduction and immunology.

Spontaneous cerebellar primitive neuroectodermal tumor in a juvenile cynomolgus monkey (Macaca fascicularis)

A neoplastic mass compressing the left cerebellar hemisphere and hindbrain was observed at trimming in a 3&frac12;-year-old male cynomolgus monkey from a control dose group. Microscopically, the neoplastic mass was nonencapsulated, invasive, and showed two morphological patterns. The predominant area consisted of densely packed undifferentiated, polygonal to spindle cells arranged in vague sheets supported by a scant fibrovascular stroma. The other area was less cellular and composed of round neoplastic cells separated by eosinophilic fibrillar material. Immunohistochemical staining for vimentin, synaptophysin, glial fibrillary acidic protein, neuron-specific enolase, neurofilament, and S-100 confirmed the presence of primitive undifferentiated neuroectodermal cells and some cells with neuronal or glial differentiation. On the basis of histopathology and immunohistochemical findings, a diagnosis of cerebellar primitive neuroectodermal tumor with neuronal and glial differentiation was made. Primitive neuroectodermal tumors are rare in animals including nonhuman primates; this is the first published report in this species.

Spontaneous Thymoma in a Juvenile Cynomolgus Macaque (Macaca fascicularis)

A single, solid, yellow-white thymic mass was found at necropsy of a two-year-old female cynomolgus macaque from a four-week, repeat-dose toxicity and immunogenicity study. Microscopically, the mass was multilobular and well encapsulated, surrounded by a thick connective tissue capsule, and composed of dense sheets of elongate or spindle-shaped cells and large cystic cavities separated by thick connective tissue stroma. Normal thymus was adjacent to the mass, but it was compressed. Within the mass were abundant interspersed Hassall’s corpuscles; individual and small clusters of mature, small lymphocytes; scattered eosinophils; large areas of necrosis; focal mineralization; and cholesterol clefts. An interesting feature was the presence of large multinucleated giant cells, which varied widely in size and nuclear number. Immunohistochemical staining for two lymphocyte markers and two structural proteins confirmed the identity of the neoplastic spindle cells and other cellular components. There was no evidence of vascular invasion or metastasis. Features of the thymoma indicated it was a pre-existing condition and not treatment related.

Diagnosis and prevalence of uterine leiomyomata in female chimpanzees (Pan troglodytes)

Uterine leiomyomata are common, affecting 70-80% of women between 30 and 50 years of age. Leiomyomata have been reported for a variety of primate species, although prevalence rates and treatments have not been widely reported. The prevalence, diagnosis, and treatment of uterine leiomyomata in the Alamogordo Primate Facility and the Keeling Center for Comparative Medicine and Research were examined. Uterine leiomyomata were diagnosed in 28.4% of chimpanzees with an average age at diagnosis of 30.4 ± 8.0 years. Advanced age (>30 years) was related to an increase in leiomyomata and use of hormonal contraception was related to a decrease in leiomyomata. As the captive chimpanzee population ages, the incidence of leiomyomata among female chimpanzees will likely increase. The introduction of progesterone-based contraception for nonbreeding research and zoological chimpanzees may reduce the development of leiomyomata. Finally, all chimpanzee facilities should institute aggressive screening programs and carefully consider treatment plans.

Critical Review of Preclinical Approaches to Evaluate the Potential of Immunosuppressive Drugs to Influence Human Neoplasia

Many immunosuppressive drugs are associated with an increased risk of B-cell lymphoma, squamous cell carcinoma, and Kaposi sarcoma. Thirteen immunosuppressive drugs have been tested in 2-year carcinogenicity studies (abatacept; azathioprine; busulfan; cyclophosphamide; cyclosporine; dexamethasone; everolimus; leflunomide; methotrexate; mycophenolate mofetil; prednisone; sirolimus; and tacrolimus) and in additional models including neonatal and genetically modified mice; chemical, viral, ultraviolet, and ionizing radiation co-carcinogenesis, and in models with transplanted tumor cells. The purpose of this review is to outline the mechanisms by which immunosuppressive drugs can influence neoplasia, to summarize the available preclinical data on the 13 drugs, and to critically review the performance of the models. A combination of primary tumor and metastasis assays conducted with transplanted cells may provide the highest value for hazard identification and can be applied on a case-by-case basis. However, for both small molecules and therapeutic proteins, determining the relative risk to patients from preclinical data remains problematic. Classifying immunosuppressive drugs based on their mechanism of action and hazard identification from preclinical studies and a prospective pharmacovigilance program to monitor carcinogenic risk may be a feasible way to manage patient safety during the clinical development program and postmarketing.

Evolution in health and medicine Sackler colloquium: Evolution of the human lifespan and diseases of aging: roles of infection, inflammation, and nutrition

Humans have evolved much longer lifespans than the great apes, which rarely exceed 50 years. Since 1800, lifespans have doubled again, largely due to improvements in environment, food, and medicine that minimized mortality at earlier ages. Infections cause most mortality in wild chimpanzees and in traditional forager-farmers with limited access to modern medicine. Although we know little of the diseases of aging under premodern conditions, in captivity, chimpanzees present a lower incidence of cancer, ischemic heart disease, and neurodegeneration than current human populations. These major differences in pathology of aging are discussed in terms of genes that mediate infection, inflammation, and nutrition. Apolipoprotein E alleles are proposed as a prototype of pleiotropic genes, which influence immune responses, arterial and Alzheimer's disease, and brain development.

Clinical and research searching on the wild side: exploring the veterinary literature

Zoological medicine furthers the health and well-being of captive and free-ranging wild animals. Effective information retrieval of the zoological medicine literature demands searching multiple databases, conference proceedings, and organization websites using a wide variety of keywords and controlled vocabulary. Veterinarians, residents, students, and the librarians who serve them must have patience for multiple search iterations to capture the majority of the available knowledge. The complexities of thorough literature searches are more difficult for nondomestic animal clinical cases and research reviews as demonstrated by three search requests involving poisonous snakes, a gorilla, and spiders. Expanding and better disseminating the knowledgebase of zoological medicine will make veterinary searching easier.

Pheochromocytoma in Six New World Primates

Six New World primates, including 2 golden lion tamarins (Leontopithecus rosalia), 2 cotton-top tamarins (Saguinus o. oedipus), 1 black howler monkey (Alouatta caraya), and 1 black-handed spider monkey (Ateles g. geoffroyi), were diagnosed with unilateral (4/6) or bilateral (1/6) adrenal or extra-adrenal (1/6) pheochromocytoma by light microscopy and immunohistochemical staining for chromogranin A. Overt invasive behavior or metastases were not observed in any primate, and thus these neoplasms were considered benign. All primates either died spontaneously (4/6) or were euthanatized (2/6) as a result of concurrent malignant neoplasia, infection, renal disease, or a combination of several disease processes. Although we did not determine whether these pheochromocytomas were functional, all 6 primates had myocardial fibrosis, and some had arteriosclerosis.

Endometrial and cervical polyps in 22 baboons (Papio sp.), 5 cynomolgus macaques (Macaca fascicularis) and one marmoset (Callithrix jacchus)

BACKGROUND

Endometrial and cervical polyps are masses of endometrium or cervical epithelium that bulge into the uterine or cervical lumen. The physiopathology and contributing factors of endometrial polyps development are still unknown.

METHODS

Clinical and pathology records of 28 non-human primates with histologically confirmed endometrial and cervical polyps were reviewed. Twenty-one baboons with endometrial polyps were evaluated for age at diagnosis, body weight, menstrual cycle length, presence of endometriosis and adenomyosis and number of offspring, cesarean sections, and stillbirths.

RESULTS

Endometrial polyps in baboons were associated with increased age, decreased menstrual cycle lengths, endometriosis, and decreased parity. No differences were found for weight, adenomyosis, or number of cesarean sections or stillbirths.

CONCLUSIONS

Baboons are a promising model for the study of endometrial polyps because of their similarity to humans in both the development of endometrial polyps and association of many of the same risk factors.

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.