Gastrointestinal tract pathology of the owl monkey (Aotus spp.).

Owl monkeys are small nocturnal new world primates in the genus Aotus that are most used in biomedical research for malaria. Cardiomyopathy and nephropathy are well-described common diseases contributing to their morbidity and mortality; less is known about lesions affecting the gastrointestinal tract. Records from a 14-year period (2008-2022) at the Keeling Center for Comparative Medicine and Research were queried to identify instances of spontaneous gastrointestinal disease that directly contributed to the cause of death from the 235 adult owl monkeys submitted for necropsy. Of the 235, 10.6% (25/235) had gastrointestinal disease listed as a significant factor that contributed to morbidity and mortality. Diagnoses included candidiasis (3/25), gastric bloat (4/25), and intestinal incarceration and ischemia secondary (11/25), which included intussusception (4/25), mesenteric rent (3/25), strangulating lipoma (2/25), intestinal torsion (1/25), and an inguinal hernia (1/25). Intestinal adenocarcinomas affecting the jejunum (4/25) were the most common neoplasia diagnosis. Oral squamous cell carcinoma (1/25) and intestinal lymphoma (2/25) were also diagnosed. This report provides evidence of spontaneous lesions in the species that contribute to morbidity and mortality.

Follicular Atresia, Cell Proliferation, and Anti-Mullerian Hormone in Two Neotropical Primates (Aotus nancymae and Sapajus macrocephalus).

This study evaluated the follicular atresia, cell proliferation, and anti-Mullerian hormone action in Aotus nancymae and Sapajus macrocephalus during three sexual phases (follicular, luteal, and gestational). Follicular quantification and immunolocalization of Caspase-3 protein, B-cell lymphoma 2 (BCL-2), proliferating cell nuclear antigen (PCNA), and anti-Mullerian hormone (AMH) were performed. A significant difference in the quantification between preantral and antral follicles, with a progressive decrease in the antrals, was identified. Protein and hormonal markers varied significantly between follicle cell types (A. nancymae p = 0.001; S. macrocephalus, p = 0.002). Immunostaining in the preantral and antral follicles was present in all sexual phases; for Caspase-3, in granulosa cells, oocytes, and stroma; for BCL-2, in granulosa cells, oocytes, and theca; and for PCNA and AMH, in oocytes and granulosa cells. The immunostaining for Caspase-3 was more expressive in the preantral follicles (follicular phase, p < 0.05), while that for BCL-2 and PCNA was more expressive in the antral follicles of the follicular phase. The AMH was more expressive in the primary and antral follicles of nonpregnant females, in both the follicular and luteal phases. Our results contribute to understanding the ovarian follicular selection, recruitment, and degeneration of these species.

Owl Monkey Alu Insertion Polymorphisms and Aotus Phylogenetics.

Owl monkeys (genus Aotus), or "night monkeys" are platyrrhine primates in the Aotidae family. Early taxonomy only recognized one species, Aotus trivirgatus, until 1983, when Hershkovitz proposed nine unique species designations, classified into red-necked and gray-necked species groups based predominately on pelage coloration. Recent studies questioned this conventional separation of the genus and proposed designations based on the geographical location of wild populations. Alu retrotransposons are a class of mobile element insertion (MEI) widely used to study primate phylogenetics. A scaffold-level genome assembly for one Aotus species, Aotus nancymaae [Anan_2.0], facilitated large-scale ascertainment of nearly 2000 young lineage-specific Alu insertions. This study provides candidate oligonucleotides for locus-specific PCR assays for over 1350 of these elements. For 314 Alu elements across four taxa with multiple specimens, PCR analyses identified 159 insertion polymorphisms, including 21 grouping A. nancymaae and Aotus azarae (red-necked species) as sister taxa, with Aotus vociferans and A. trivirgatus (gray-necked) being more basal. DNA sequencing identified five novel Alu elements from three different taxa. The Alu datasets reported in this study will assist in species identification and provide a valuable resource for Aotus phylogenetics, population genetics and conservation strategies when applied to wild populations.

Associations between fecal cortisol and biparental care in a pair-living primate.

OBJECTIVES: We quantified variation in fecal cortisol across reproductive periods in Azara's owl monkeys (Aotus azarae) to examine physiological mechanisms that may facilitate biparental care. Specifically, we evaluated evidence for the explanation that owl monkeys have hormonal mechanisms to mobilize energy during periods when each sex is investing heavily in reproduction, that is, the gestation period for females and the infant care period for males. MATERIALS AND METHODS: Between 2011 and 2015, we monitored 10 groups of Azara's owl monkeys from a wild population in Formosa, Argentina and collected fecal samples from 26 adults (13 males, 13 females). Using enzyme-linked immunosorbent assays, we quantified fecal cortisol as a proxy for evaluating stress responses, including energetic demands, on both sexes during periods of reproduction and parental care. RESULTS: Male cortisol was lowest during periods when they were caring for young infants (<3 months) compared with periods with older infants or no infant. Female cortisol was elevated during gestation compared with other periods. Mean fecal cortisol in both males and females was lower when an infant was present compared with when females were gestating. DISCUSSION: Our results do not support the hypothesis that owl monkey males have elevated fecal cortisol during periods when they need to mobilize energy to provide intensive infant care. Our findings are also inconsistent with the Maternal Relief hypothesis. However, results from studies measuring fecal cortisol must be interpreted with care and alternative explanations, such as seasonal fluctuations in diet and thermoenergic demands, should be considered when drawing conclusions.

Lunar periodic modulation of the circadian activity rhythm in a wild North Colombian night monkey (Aotus griseimembra).

South American night monkeys (genus Aotus) are the only nocturnal simian primates. Early activity recordings in North Colombian A. griseimembra monkeys kept under semi-natural conditions and extensive chronobiological studies carried out in laboratory settings revealed a strictly nocturnal behavior and strong activity enhancing (disinhibiting) effects of moonlight or corresponding luminosities during the dark time. To check whether the results from captive individuals correspond to the behavior of wild monkeys, we carried out long-term activity recordings of a wild female A. griseimembra in a tropical rainforest near San Juan de Carare, Northern Colombia. Our data from about 150 days of continuous activity records with an "Actiwatch Mini" (CamNtech, UK) accelerometer-data logger device, confirmed: (1) strictly nocturnal behavior, (2) a pronounced bimodal activity pattern with prominent peaks during dusk and dawn, and (3) a lunar periodic modulation (masking) of the night monkey's circadian activity rhythm due to distinct activity inhibiting effects of the absence of moonlight throughout the night. The results from this wild-living tropical night monkey are consistent with those from captive conspecifics studied decades earlier.

Habitat use, fruit consumption, and population density of the black-headed night monkey, Aotus nigriceps, in southeastern Peru

The black-headed night monkey, Aotus nigriceps, has one of the largest distribution ranges of the 11 night monkey species found across Central and South America. Yet, only three studies have focused on their ecology, describing considerable variation in habitat, group composition, and population density. Therefore, we analyzed habitat use, group composition, population density, and diet of 14 groups at two field sites in southeastern Peru. All sampled groups were found in secondary tropical rainforest, often dominated by native bamboo species. Half of the observed sleeping sites were in bamboo stands, though groups also emerged from cane thickets and lianas. This contrasts with other Aotus studies which have found groups living in tree cavities and lianas. Population density estimates for both sites were 19 and 50 individuals per km2, outside the range previously reported for A. nigriceps (31−34 individuals per km2). We recovered seeds of 12 species from fecal samples over the course of two field seasons, belonging mainly to Cecropiaceae, Piperaceae and Moraceae. Our results suggest that the black-headed night monkey in Peru can survive and even thrive in secondary forest, feeding extensively on pioneer species, occupying a range of forest types, all while living near human settlements. (AU)

Alpha satellite DNA-repeat OwlAlp1 forms centromeres in Azara's owl monkey.

Centromeres play crucial roles in faithful chromosome segregation and genome integrity. In simian primates, centromeres possess tandem array of alpha satellite DNA (also referred to as alphoid DNA). Average sizes of alpha satellite repeat units vary between species, for example, 171 bp in human and 343-344 bp in many platyrrhini species (New World monkeys). Interestingly, Azara's owl monkey (Aotus azarae), a platyrrhini species, possesses alpha satellite DNA of two distinct unit sizes, OwlAlp1 (185 bp) and OwlAlp2 (344 bp), both of which present as megasatellite DNAs in the genome. It is, however, unknown which repeat sequence is responsible for functional centromere formation. To investigate the localization of centromeres in vivo, we carried out chromatin immunoprecipitation (ChIP) assay using Azara's owl monkey cells. We found that CENP-A, a histone H3 variant essential for centromere formation, was enriched at OwlAlp1, but not at OwlAlp2. Moreover, CENP-A was detected only at constricted regions of chromosomes by immunofluorescent microscopy. In contrast, trimethylation of histone H3-K9 (H3K9me3), a marker of heterochromatin, was enriched at both OwlAlp1 and OwlAlp2. Our results show that the shorter alpha satellite repeat, OwlAlp1, is selectively used for centromere formation in this monkey.

Reproductive Longevity Predicts Mutation Rates in Primates.

Mutation rates vary between species across several orders of magnitude, with larger organisms having the highest per-generation mutation rates. Hypotheses for this pattern typically invoke physiological or population-genetic constraints imposed on the molecular machinery preventing mutations [1]. However, continuing germline cell division in multicellular eukaryotes means that organisms with longer generation times and of larger size will leave more mutations to their offspring simply as a byproduct of their increased lifespan [2, 3]. Here, we deeply sequence the genomes of 30 owl monkeys (Aotus nancymaae) from six multi-generation pedigrees to demonstrate that paternal age is the major factor determining the number of de novo mutations in this species. We find that owl monkeys have an average mutation rate of 0.81 × 10-8 per site per generation, roughly 32% lower than the estimate in humans. Based on a simple model of reproductive longevity that does not require any changes to the mutational machinery, we show that this is the expected mutation rate in owl monkeys. We further demonstrate that our model predicts species-specific mutation rates in other primates, including study-specific mutation rates in humans based on the average paternal age. Our results suggest that variation in life history traits alone can explain variation in the per-generation mutation rate among primates, and perhaps among a wide range of multicellular organisms.

Morphological analyses of the retinal photoreceptor cells in the nocturnally adapted owl monkeys.

Owl monkeys are the only one species possessing the nocturnal lifestyles among the simian monkeys. Their eyes and retinas have been interested associating with the nocturnal adaptation. We examined the cellular specificity and electroretinogram (ERG) reactivity in the retina of the owl monkeys by comparison with the squirrel monkeys, taxonomically close-species and expressing diurnal behavior. Owl monkeys did not have clear structure of the foveal pit by the funduscope, whereas the retinal wholemount specimens indicated a small-condensed spot of the ganglion cells. There were abundant numbers of the rod photoreceptor cells in owl monkeys than those of the squirrel monkeys. However, the owl monkeys' retina did not possess superiority for rod cell-reactivity in the scotopic ERG responses. Scanning electron microscopic observation revealed that the rod cells in owl monkeys' retina had very small-sized inner and outer segments as compared with squirrel monkeys. Owl monkeys showed typical nocturnal traits such as rod-cell dominance. However, the individual photoreceptor cells seemed to be functionally weak for visual capacity, caused from the morphological immaturity at the inner and outer segments.

The role of intragroup agonism in parent-offspring relationships and natal dispersal in monogamous owl monkeys (Aotus azarae) of Argentina.

Agonistic behaviors are common in many group-living taxa and may serve a variety of functions, ranging from regulating conflicts over reproduction to defending food resources. However, high rates of agonism are not expected to occur among close relatives or individuals in established mating relationships, which are characteristics of monogamous groups. To contribute to our understanding of agonism within socially monogamous groups, we collected behavioral and demographic data from Azara's owl monkeys (Aotus azarae) in the Gran Chaco of Argentina over 14 years. We examined factors related to age, sex, kinship, and behavioral context to evaluate predictions of the hypotheses that agonism functions to regulate dispersal and that it mediates competition for food and/or mates. Intragroup agonism was relatively rare: the group rate was approximately one event every three and a half hours. Rates of agonism were generally similar for both sexes, but there were marked differences among age categories. Agonism performed by adults was more frequently directed at subadults than at younger offspring. In contrast, agonistic interactions involving infants were very rare. Among interactions between adults and subadults, adults were much more frequently the actors than the recipients, suggesting that agonism from adults may influence natal dispersal of subadults. Agonistic events were most frequent during foraging, but also occurred more frequently than expected during bouts of social behavior. Overall, our results suggest that agonism in owl monkeys serves as a mechanism for regulating dispersal, and also likely plays a role in mediating mating and feeding competition.

Owl monkey CCR5 reveals synergism between CD4 and CCR5 in HIV-1 entry.

Studying HIV-1 replication in the presence of functionally related proteins from different species has helped define host determinants of HIV-1 infection. Humans and owl monkeys, but not macaques, encode a CD4 receptor that permits entry of transmissible HIV-1 variants due to a single residue difference. However, little is known about whether divergent CCR5 receptor proteins act as determinants of host-range. Here we show that both owl monkey (Aotus vociferans) CD4 and CCR5 receptors are functional for the entry of transmitted HIV-1 when paired with human versions of the other receptor. By contrast, the owl monkey CD4/CCR5 pair is generally a suboptimal receptor combination, although there is virus-specific variation in infection with owl monkey receptors. Introduction of the human residues 15Y and 16T within a sulfation motif into owl monkey CCR5 resulted in a gain of function. These findings suggest there is cross-talk between CD4 and CCR5 involving the sulfation motif.

Hormonal correlates of development and natal dispersal in wild female owl monkeys (Aotus azarae) of Argentina.

Pair-living and socially monogamous primates typically do not reproduce before dispersing. It is currently unclear whether this reproductive suppression is due to endocrine or behavioral mechanisms. Cooperatively breeding taxa, like callitrichids, may forego reproduction in natal groups because they reap inclusive fitness benefits and/or they are avoiding inbreeding. However, neither of these benefits of delayed reproduction appear to adequately explain the lack of reproduction prior to leaving the natal group in pair-living monogamous species. In this study, we determined whether wild Azara's owl monkeys (Aotus azarae) in the Argentinean Chaco establish reproductive maturity prior to dispersing. We utilized 635 fecal extracts to characterize reproductive hormone profiles of 11 wild juvenile and subadult females using enzyme immunoassays. Subadult females showed hormone profiles indicative of ovulatory cycling and had mean PdG and E1G concentrations approximately five times higher than juveniles. Contrary to expectations from the inbreeding avoidance hypothesis, female owl monkeys do not delay puberty, but rather commence ovarian cycling while residing in their natal group. Still, subadults appear to have a period during which they experience irregular, non-conceptive cycles prior to reproducing. Commencing these irregular cycles in the natal group may allow them to develop a state of suspended readiness, which could be essential to securing a mate, while avoiding costs of ranging solitarily. Our results indicate that reproductive suppression in female owl monkeys is not due to endocrine suppression. We suggest that adults likely use behavioral mechanisms to prevent subadults from reproducing with unrelated adult males in their natal group.

Socialization of adult owl monkeys (Aotus sp.) in Captivity.

Social housing has often been recommended as one-way to address the psychological well-being of captive non-human primates. Published reports have examined methods to socialize compatible animals by forming pairs or groups. Successful socialization rates vary depending on the species, gender, and environment. This study presents a retrospective look at pairing attempts in two species of owl monkeys, Aotus nancymaae and A. azarae, which live in monogamous pairs in the wild. The results of 477 pairing attempt conducted with captive, laboratory housed owl monkeys and 61 hr of behavioral observations are reported here. The greatest success pairing these owl monkeys occurred with opposite sex pairs, with an 82% success rate. Opposite sex pairs were more successful when females were older than males. Female-female pairs were more successful than male-male (MM) pairs (62% vs 40%). Successful pairs stayed together between 3 and 7 years before the animals were separated due to social incompatibility. Vigilance, eating, and sleeping during introductions significantly predicted success, as did the performance of the same behavior in both animals. The results of this analysis show that it is possible to give captive owl monkeys a social alternative even if species appropriate social partners (i.e., opposite sex partners) are not available. The focus of this report is a description of one potential way to enhance the welfare of a specific new world primate, the owl monkey, under laboratory conditions. More important is how the species typical social structure of owl monkeys in nature affects the captive management of this genus. Am. J. Primatol. 79:e22521, 2017. © 2015 Wiley Periodicals, Inc.

Genetic diversity of Klebsiella pneumoniae isolates during an outbreak in a non-human primate research colony.

BACKGROUND: Klebsiella pneumoniae can be a serious pathogen in non-human primates, particularly Neotropical monkeys. METHODS: During a K. pneumoniae outbreak in an owl monkey research colony, 13 K. pneumoniae isolates were DNA fingerprinted by automated repetitive extragenic palindromic-polymerase chain reaction and the profiles compared to isolates obtained from other non-human primate species during the same time period and isolates from previous outbreaks. RESULTS: Eleven different types of K. pneumoniae were circulating in the owl monkey colony at the time of the outbreak. When comparing owl monkey isolates relatedness to previous colony outbreak isolates and squirrel monkey and capuchin monkey isolates, all were different. CONCLUSIONS: These results agree with recent reports where K. pneumoniae nosocomial isolates in hospital settings can have high genetic diversity, and multiple strains can be circulating simultaneously. This potential genetic diversity should be considered when designing strategies for controlling K. pneumoniae outbreaks in captive non-human primate colonies.

Can colour vision re-evolve? Variation in the X-linked opsin locus of cathemeral Azara's owl monkeys (Aotus azarae azarae).

BACKGROUND: Do evolutionary specializations lead to evolutionary constraint? This appears plausible, particularly when specialization leads to loss of complex adaptations. In the owl monkey lineage, nocturnality clearly arose from a diurnal ancestor. This behavioural shift was accompanied by morphological changes in the eye and orbit and complete loss of colour vision via missense mutations in the gene encoding the short-wave sensitive visual pigment (SWS opsin). Interestingly, at least one subspecies of owl monkey, Azara's owl monkey (Aotus azarae azarae), has regained activity in daylight. Given that all primate species that are active in daylight, including primarily diurnal species and species that are active during both day and night, have at least dichromatic colour vision, it seems reasonable to propose that dichromacy would be adaptive in A. a. azarae. With a disabled SWS opsin, the main avenue available for Azara's owl monkeys to re-evolve colour vision is via a polymorphism in the intact X-linked opsin locus, which commonly occurs in other New World monkeys. To examine this possibility we assayed variation in the X-linked opsin of A. a. azarae, focusing on the three exons (3, 4 and 5) that control spectral sensitivity. RESULTS: We found low opsin genetic variation on a population level, and no differences at the three main sites that lead to variation in spectral sensitivity in the opsins of other New World monkeys. Two rare alleles with single amino acid variants are segregating in the population, but previous functional studies indicate that these are unlikely to affect spectral sensitivity. CONCLUSIONS: Genetic constraint on the re-evolution of colour vision is likely operating in Azara's owl monkey, which may affect the niche that this subspecies is able to occupy.

Intracytoplasmic sperm injection into oocytes matured in vitro and early embryonic development in the owl monkey (Aotus lemurinus).

Purpose: We explored the possibility of employing intracytoplasmic sperm injection (ICSI), involving oocytes and sperm of owl monkeys, to increase the availability of this species for investigations relating to malaria, etc., by increasing the number of animals in our laboratory. Methods: Two owl monkeys (a female and a male), raised at the Amami Laboratory of the University of Tokyo, were used. Follicular oocytes surrounded with cumulus cells were cultured in vitro for approximately 25 h and cumulus cells were removed with 0.1 % hyaluronidase. Because of the poor motility of caudal epididymal sperm, sperm were injected without adding polyvinylpyrrolidone to immobilize them. The ICSI procedure was performed by an individual with considerable experience of human ICSI. Results: We were able to produce two owl monkey embryos using ICSI of oocytes that matured to MII stage. Both embryos reached the 10-cell stage at 98 h after ICSI and showed signs of compaction, but failed to cleave further. Conclusions: Although we successfully produced owl monkey embryos after ICSI, the embryos did not develop to the blastocyst stage. Many parameters need to be studied further, including superovulation, selection of culture media, and selection of good quality sperm in order to achieve successful ICSI in the owl monkey.

Retinotopic organization of extrastriate cortex in the owl monkey--dorsal and lateral areas.

Dense retinotopy data sets were obtained by microelectrode visual receptive field mapping in dorsal and lateral visual cortex of anesthetized owl monkeys. The cortex was then physically flatmounted and stained for myelin or cytochrome oxidase. Retinotopic mapping data were digitized, interpolated to a uniform grid, analyzed using the visual field sign technique-which locally distinguishes mirror image from nonmirror image visual field representations-and correlated with the myelin or cytochrome oxidase patterns. The region between V2 (nonmirror) and MT (nonmirror) contains three areas-DLp (mirror), DLi (nonmirror), and DLa/MTc (mirror). DM (mirror) was thin anteroposteriorly, and its reduced upper field bent somewhat anteriorly away from V2. DI (nonmirror) directly adjoined V2 (nonmirror) and contained only an upper field representation that also adjoined upper field DM (mirror). Retinotopy was used to define area VPP (nonmirror), which adjoins DM anteriorly, area FSTd (mirror), which adjoins MT ventrolaterally, and TP (mirror), which adjoins MT and DLa/MTc dorsoanteriorly. There was additional retinotopic and architectonic evidence for five more subdivisions of dorsal and lateral extrastriate cortex-TA (nonmirror), MSTd (mirror), MSTv (nonmirror), FSTv (nonmirror), and PP (mirror). Our data appear quite similar to data from marmosets, though our field sign-based areal subdivisions are slightly different. The region immediately anterior to the superiorly located central lower visual field V2 varied substantially between individuals, but always contained upper fields immediately touching lower visual field V2. This region appears to vary even more between species. Though we provide a summary diagram, given within- and between-species variation, it should be regarded as a guide to parsing complex retinotopy rather than a literal representation of any individual, or as the only way to agglomerate the complex mosaic of partial upper and lower field, mirror- and nonmirror-image patches into areas.

Ovarian function in captive owl monkeys (Aotus nancymaae and A. vociferans).

BACKGROUND: Ovarian function and morphology of owl monkeys (Aotus spp.) is inadequately known, but it is essential to describe this organ in detail to better understand reproductive patterns of the species. METHODS: This study reports the anatomical and histological features of the ovaries from 41 owl monkeys, considering their reproductive status and parity. RESULTS: The corpora lutea (CL) and reproductive state had a significant effect on ovarian volume. Follicles were observed in both pregnant and non-pregnant subjects. All females in the luteal phase and pregnant females showed at least one cyclic or pregnancy CL. Mean ovulation rate was 1.89 CL/female, and the mean ovum mortality was 37.5%. There were no significant differences in ovarian volume related to parity. CONCLUSIONS: These results contribute to the scarce information available on the reproductive biology of owl monkeys and can aid in the development of biotechnologies involved in assisted reproduction.

Functional morphology of the tubular genital organs in the female owl monkey (Aotus spp.).

BACKGROUND: Studies on reproductive morphology are important to understand the reproductive cycle of non-human primates. METHODS: This study describes the functional morphology of the adult female tubular genital organs in 41 Aotus (12.8 ± 6.8 years old, ranging from 3 to 25 years), with respect to reproductive status and number of parturitions. RESULTS: In females with developing embryos, endometrial glands showed a higher secretion than other females, and the embryo implantation occupied this secretive endometrium. Changes in the thickening, number of layers, and keratinization in the vaginal epithelium suggest that vaginal cytology may be an indicator of the estrous cycle. Non-pregnant multiparous females had a larger uterine body than nulliparous females. Number of parturitions and reproductive state had an impact on tubular genital organs in female owl monkeys. CONCLUSIONS: These results can be useful for the development of biotechnologies of reproduction and for improvement of the management of this species.

Avaliação ultrassonográfica e mensurações das glândulas adrenais em primatas não humanos neotropicais: mico-de-cheiro (Saimiri sciureus), macaco-da-noite (Aotus azarae infulatus) e bugio-ruivo (Alouatta guariba clamitans) / Adrenal glands measurements and ultrasound evaluation in nonhuman primates: squirrel monkey (Saimiri sciureus), owl monkey (Aotus azarae infulatus) and howler monkey (Alouatta guariba clamitans)

As glândulas adrenais possuem funções endócrinas relacionadas a múltiplas funções vitais, estando intimamente relacionadas à capacidade do animal em se adaptar ao estresse. O exame ultrassonográfico é o método diagnóstico de escolha para avaliação das glândulas em diferentes espécies. Considerando a escassa literatura, questiona-se se as doenças adrenais em primatas não humanos são incomuns ou subdiagnosticadas, havendo a hipótese desse fato ser determinado pela falta de parâmetros. Objetivou-se descrever as características ultrassonográficas das glândulas adrenais para três espécies de primatas não humanos mantidas em cativeiro: Saimiri sciureus (mico-de-cheiro), Aotus azarae infulatus (macaco-da-noite) e Alouatta guariba clamitans (bugio-ruivo). Conclui-se que é possível a identificação das glândulas adrenais por meio de exame ultrassonográfico, sendo que os padrões de referência foram estabelecidos com sucesso para as espécies em questão. Ressalta-se que a adequação de animais em ambientes estressantes é frequentemente acompanhada por uma hipertrofia das glândulas adrenais, portanto deve-se levar em consideração que as mensurações realizadas nesse estudo foram estabelecidas em animais de cativeiro...

The adrenal glands have endocrine functions related to multiple vital functions and are closely related to the animal's ability to adapt to stress. The ultrasound is the diagnostic method of choice for evaluation of glands in different species. Considering the scarce literature, one may question whether the adrenal disorders in nonhuman primates are uncommon or underdiagnosed, and a hypothesis exists that this fact is determined by the lack of parameters. The goal is to describe the sonographic features of the adrenal glands for three species of nonhuman primates kept in captivity: squirrel monkey (Saimiri sciureus), owl monkey (Aotus azarae infulatus) and howler monkey (Alouatta guariba clamitans). It is concluded that it is possible to identify the adrenal glands by ultrasound, and the reference standards have been established successfully for the species in question. It is noteworthy that the adaptation of animals in many stressful environments is often accompanied by a hypertrophy of the adrenal glands, so one should take into account that the measurements performed in this study were established in captive animals...