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PubMed1978

About the existence and endings of nerve fibres in the Cebus apella monkey's upper lip.

In the present research, fibres and nerve endings of upper lip of the Cebus apella monkey have been studied. Upper lip of 8 Cebus apella were analysed. The pieces were prepared according to the technic of Castro's silver impregnation and submitted to serial sections 8 micra thick. Our results permit to conclude that the Cebus apella monkey's upper lip has a great number of free nerve endings, between connective and epithelial layers in the mucosa and in the skin. The aspects of nerve fibres and their free and organized endings, like Meissner's corpuscles, in the upper lip mucosa of the monkey, allow comparison of similarity with those of man. The nerve endings in the lip skin of the Cebus monkey are also abundant, characterizing the hair follicles and sebaceous glands innervation and the free nerve endings encountered in the connective tissue as well as in the sub-epithelial layer.

Animals↗
PubMed1978

Colposcopic examination of the cervix of cebus monkeys.

A total of 410 colposcopic examinations were performed on 188 female cebus monkeys that were under study to determine the oncogenic potential of herpes simplex virus type 2 in this genus. A split-cone vaginal speculum was developed that permitted good observation of the vaginal cervix in the cebus monkey. The cervical anatomy of cebus monkeys was found to differ from that of humans in that the surface of the animal cervix was more papilliform, with thinner squamous epithelium, and the squamocolumnar junction lay within the endocervical canal. Therefore, the ability to detect abnormalities in the cervical epithelium by colposcopic examination in the cebus monkey was restricted to vascular changes in the squamous epithelium. After 100 examinations, several vascular patterns were distinguishable and interpretations of these patterns were compared with cytologic findings on the same animals. Findings by both cytology and colposcopy were mild in nature; no carcinoma was detected. Colposcopic and cytologic findings correlated at a level of 84%. More abnormalities were detected with colposcopy than with use of cytologic techniques.

Animals↗
PubMed1999

The ecological role of the prehensile tail in white-faced capuchins (Cebus capucinus).

Prehensile tails appear to have evolved at least twice in platyrrhine evolution. In the atelines, the tail is relatively long and possesses a bare area on the distal part of its ventral surface that is covered with der-matoglyphs and richly innervated with Meissner's corpuscles. In contrast, the prehensile tail of Cebus is relatively short, fully haired, and lacks specialized tactile receptors. Little is currently known regarding tail function in capuchins, and whether their prehensile tail serves a greater role in feeding or traveling. In this paper we examine patterns of positional behavior, substrate preference, and tail use in wild white-faced capuchins (Cebus capucinus) inhabiting a wet tropical forest in northeastern Costa Rica. Observational data were collected over the course of 3 months on adult capuchins using an instantaneous focal animal time sampling technique. Differences in the frequency and context of tail use, and the estimated amount of weight support provided by the tail relative to other appendages during feeding/foraging and traveling were used as measures of the ecological role of this specialized organ in capuchin positional behavior. During travel, quadrupedal walking, leaping, and climbing dominated the capuchin positional repertoire. The capuchin tail provided support in only 13.3% of travel and was principally employed during below branch locomotor activities. In contrast, tail-assisted postures accounted for 40.6% of all feeding and foraging records and occurred primarily in two contexts. The tail was used to suspend the individual below a branch while feeding, as well as to provide leverage and weight support in above-branch postures associated with the extraction of prey from difficult to search substrates. A comparison of tail use in Cebus, with published data on the atelines indicates that both taxa possess a grasping tail that is capable of supporting the animal's full body weight. In capuchins and howling monkeys, the tail appears to be used more frequently and serves a greater weight-bearing role during feeding than during traveling. In Ateles, and possibly Brachyteles, and Lagothrix, however, the prehensile tail serves a dual role in both feeding and forelimb suspensory locomotion. Additional relationships between white-faced capuchin feeding, positional behavior, extractive foraging techniques, and prehensile tail use are discussed.

Animals↗
PubMed1997

Transfer of tools and food between groups of tufted capuchins (Cebus apella).

This research examined tool and food transfer between two groups of tufted capcuhin monkeys (Cebus apella). Subjects in one group transferred stones to subjects in a second group who in turn used the stones as cutting tools and then transferred food to subjects in the first group. Aspects of the capuchins' behavior are similar to those described for food-sharing in Cebus, cooperative tool use in Papio, and tool and food exchange in Pan. We propose that tool use and food-sharing facilitate tool and food transfer between captive groups of Cebus apella.

Animals↗
PubMed2005

Color-vision polymorphism in wild capuchins (Cebus capucinus) and spider monkeys (Ateles geoffroyi) in Costa Rica.

New World monkeys are unique in exhibiting a color-vision polymorphism due to an allelic variation of the red-green visual pigment gene. This makes these monkeys excellent subjects for studying the adaptive evolution of the visual system from both molecular and ecological viewpoints. However, the allele frequencies of the pigments within a natural population have not been well investigated. As a first step toward understanding the relationship between vision and behavior, we conducted color-vision typing by analyzing fecal DNA from two wild groups of white-faced capuchin monkeys (Cebus capucinus) and one group of black-handed spider monkeys (Ateles geoffroyi) inhabiting Santa Rosa National Park of Costa Rica. All color-typed monkeys were individually identified. In C. capucinus and A. geoffroyi we found three and two pigment types, respectively, and the spectral mechanism that created one of the two Ateles pigments was found to be novel. In one Cebus group and the Ateles group, all alleles were present, whereas in the other Cebus group only two alleles were found, with one allele predominating. This was likely due to the effect of close inbreeding, indicating that wild populations can exhibit a variety of allele compositions. This result also suggests that the color-vision polymorphism can be easily distorted by natural factors, such as inbreeding, skewing the population structure.

Animals↗
PubMed1980

Fluorescence and electron microscopical observations on the amine-accumulating neurons of the cebus monkey retina.

The organization of the Cebus monkey regina was analysed after the intraocular injection of 5,6-dihydroxytryptamine. This amine was taken up not only by the previously known dopaminergic neurons, but also by a set of indoleamine-accumulating neurons, whose processes are confined to the inner plexiform layer. The synaptic contacts of the dopaminergic neurons were analysed in the electron microscope after the processes of the indoleamine-accumulating neurons were destroyed by the intravitreal injection of the neurotoxic indoleamine, 5,7-dihydroxytryptamine. The subsequent injection of 5,6-dihydroxytryptamine induces certain changes in the dopaminergic neurons which accumulate the substance: electron-dense cores appear in the synaptic vesicles, and increased electron-density of mitochodrial and cellular membranes is often observed. The dopaminergic neurons were found to be presynaptic to amacrine cell perikarya and processes in the inner plexiform layer. In the outer plexiform layer they were presynaptic to both bipolar and horizontal cells, but they did not contact photoreceptors. The dopaminergic neurons received synapses only in the inner plexiform layer, from amacrine cell processes. It is inferred that in Cebus most dopaminergic neurons belong to a special class of retinal neuron, the interplexiform cells, which appear to transmit information centrifugally within the retina, from the inner to the outer plexiform layers. There are considerable similarities between the synaptology of the dopaminergic interplexiform neurons in the Cebus monkey and the goldfish retina, and the function of interplexiform neurons may therefore be similar in these two species.

5,6-Dihydroxytryptamine↗
PubMed1991

A quantitative analysis of cytochrome oxidase-rich patches in the primary visual cortex of Cebus monkeys: topographic distribution and effects of late monocular enucleation.

We have studied the tangential distribution of cytochrome oxidase (cytox)-rich patches in striate cortex of normal and monocularly enucleated Cebus apella monkeys. Patch spatial density and patch cross-sectional area were analysed in cytox-reacted tangential sections of flat-mounted preparations of V1. In the upper cortical layers of V1, and specially in the middle of layer III, the Cebus has well-delimited cytox-rich patches. Rows of patches are less conspicuous in Cebus than in Old World monkeys. The spatial density of patches is nearly constant throughout the binocular field representation in V1, with a mean value of 4 patches per mm2. In the monocular portions of V1, however, patch spatial density diminishes. In most cases, mean patch cross-sectional area decreases slightly towards the representation of the periphery in V1. However, patches in the representation of the monocular crescent tend to be larger than those in the adjacent binocular representation. The small variation of cytox patch topography with eccentricity contrasts with the large variation of cortical point-image size in V1. In monocularly enucleated monkeys, patches are larger and darker above and below the ocular dominance stripes of the remaining eye than in the alternate stripes. After long-term enucleation, the patches corresponding to the remaining eye columns appeared larger than in normal controls. In contrast, there is no difference in size between the patches located in the deprived and undeprived monocular crescent representations, although both patch and interpatch regions are darker staining in the latter. These results suggest the existence of competitive interactions which modify the cortical intrinsic organization even in adult monkeys.

Animals↗
PubMed2004

Transport of tools to food sites in tufted capuchin monkeys (Cebus apella).

Tool use and transport represent cognitively important aspects of early hominid evolution, and nonhuman primates are often used as models to examine the cognitive, ecological, morphological and social correlates of these behaviors in order to gain insights into the behavior of our early human ancestors. In 2001, Jalles-Filho et al. found that free-ranging capuchin monkeys failed to transport tools (stones) to food sites (nuts), but transported the foods to the tool sites. This result cast doubt on the usefulness of Cebus to model early human tool-using behavior. In this study, we examined the performance of six captive tufted capuchin monkeys (Cebus apella) in a tool transport task. Subjects were provided with the opportunity to transport two different tools to fixed food reward sites when the food reward was visible from the tool site and when the food reward was not visible from the tool site. We found that the subjects quickly and readily transported probing tools to an apparatus baited with syrup, but rarely transported stones to a nut-cracking apparatus. We suggest that the performance of the capuchins here reflects an efficient foraging strategy, in terms of energy return, among wild Cebus monkeys.

Animals↗
PubMed2005

Craniodental biomechanics and dietary toughness in the genus Cebus.

The tufted capuchin (Cebus apella) has been used in a number of comparative studies to represent a primate with craniofacial morphology indicative of hard-object feeding. Researchers have specifically referred to the tufted capuchin as a seed predator. Craniofacial features exhibited by the tufted capuchin, such as thick cortical bone in the mandibular corpus and symphysis, and a broad face associated with large masticatory muscles, permit the production and dissipation of relatively high masticatory forces. These morphologies, however, cannot distinguish between the tufted capuchin's propensity to exert higher forces when opening food with its anterior dentition or with its cheek teeth. It is also unclear whether these are adaptations for biting or chewing foods. This study uses a constrained lever model to compare the masticatory adaptations of C. apella to other cebids and atelids. Results show that the temporalis and masseter muscles in C. apella and C. olivaceus are more anteriorly positioned relative to nine other platyrrhine taxa. This condition, which appears to be ancestral among the Cebinae, increases force production at the incisors and canines while compromising third molar function. Cebus apella, has exaggerated this pattern. Field data on dietary toughness show that both capuchins typically select foods of low toughness, but on occasion, C. apella ingests food items of exceptional toughness. Thus, C. apella appears to maintain these biomechanical relationships by producing particularly high but relatively infrequent bite forces, particularly at the incisors and canines. However, adaptations for anterior dental use do not tightly constrain the diet of Cebus apella. This approach can be used to clarify the dietary adaptations of fossil taxa.

Anatomy, Comparative↗
PubMed1981

Conservation of replication chronology of homologous chromosome bands between four species of the genus Cebus and man.

Replication patterns after 5-bromodeoxyuridine incorporation are analyzed in chromosomes of four species of the genus Cebus (C. capucinus, C. albifrons, C. appella, and C. nigrivittatus). They are compared with those of man, taking as reference the banding analyses previously described. It was found that the high degree of conservation of chromosome structures between Cebus and man was accompanied by conservation of the DNA-replication sequence of the bands. It is assumed that this conservation during the course of evolution may apply to other mammals. Thus, replication patterns may be useful for ensuring interspecific comparisons. The only detected difference concerns late-replicating X chromosomes from normal female cells: The predominant lymphocyte pattern described in man is rare in Cebus, in which the usual lymphocyte pattern corresponds to that of human fibroblasts or to the minor human lymphocyte pattern.

Animals↗
PubMed1990

Vertebrate predation in Cebus capucinus: meat eating in a neotropical monkey.

A long-term study of two groups of white-faced capuchins (Cebus capucinus) in Santa Rosa National Park in Costa Rica provides evidence of unusually high levels of vertebrate predation compared to those reported in other field studies of Cebus. The hunting techniques for different prey types are described, and several questions concerning vertebrate predation in primates are addressed. Why is there variation between individuals and between groups in the rate of predation? Why do males hunt more than females? Previous hypotheses to explain hunting in Old World primates are applied to this Neotropical example. Finally, I argue that successful vertebrate predation can readily arise in species like Cebus, which are characterized by opportunistic foraging patterns, manipulative and cognitive skills and well-developed techniques for locating and subduing invertebrate prey.

Animals↗
PubMed1990

A comparative study of neonatal skeletal development in Cebus and other primates.

Comparisons of hand/wrist radiographs of neonatal Cebus albifrons (n = 14) and Cebus apella (n = 4) with those of Saimiri sciureus boliviensis (n = 9) and Macaca mulatta (n = 63) reveal that the cebid monkeys show much less skeletal ossification at birth than macaques. Differences in gestation time alone cannot account for the differences in skeletal maturity at birth in the two groups of monkeys. The skeletal precocity of the newborn macaques indicates that their ossification either begins earlier in gestation or proceeds at a more rapid rate, or both. This, in turn, raises questions about the timing of organogenesis and gestational comparability in cebid and cercopithecid monkeys. The advanced state of ossification seen in macaques at birth is not typical of other groups of anthropoid primates, including Cebus, Saimiri, Pan and Homo, and may represent an ontogenetic specialization.

Animals↗
PubMed1991

Electrocardiographic changes in chronic Trypanosoma cruzi infected Cebus apella monkeys.

PURPOSE: To evaluate electrocardiographic data of Cebus apella monkeys with Chagas' disease. MATERIAL AND METHODS: 53 Cebus apella monkeys (juvenile and adult of both sexes) were used: 35 as a control group and 18 inoculated four-five years ago with 3 different Trypanosoma cruzi strains (CA1, n = 10; Colombian, n = 4; Tulahuen, n = 4). RESULTS: The normal electrocardiogram (ECG) showed differences with that of man, a) high cardiac rate; b) presence of "pulmonary p" wave without pulmonary pathology. The ECT alterations found between 11 and 58 months after last inoculation were: right bundle branch block; intermittent right bundle branch block; left ventricle overload; repolarization disturbances; left anterior hemiblock; extra systole. These alterations resemble those found in humans, as well as clinical parasitological and immunological alterations. Their incidence and the time at which they appeared, seem to vary according to the route, strain, inoculum and frequency of the inoculation. Three of the monkeys died spontaneously 46, 48 and 52 months after the infections due to the natural evolution of the disease, and six were sacrificed during the follow-up. In both cases histopathological lesions were found, and their intensity was directly related to the time and resembled the human disease. CONCLUSION: The Cebus apella, as it reproduces human electrocardiographic and histopathological alterations, a short time after experimental infection, is a suitable model for the study of the different aspects of the physiopathology, immunopathology and therapeutics of the indeterminate and chronic phases of Chagas' disease.

Animals↗
PubMed1985

Limited in vivo susceptibility of the South American monkey -Cebus apella- to type 1 poliovirus: physical and histopathological observations after intraspinal inoculation.

Type 1 polioviruses (an attenuated strain, Sabin 1 LSc 2ab and a virulent strain, Mahoney) were inoculated intraspinally into the South American Cebus monkey Cebus apella. Neither physical symptoms nor histological changes in the central nervous system were observed after inoculation of attenuated Sabin strain. But the virulent Mahoney strain caused flaccid paralysis in two of three monkeys. In these two paralyzed monkeys, definite specific histological changes were observed with spreading of the lesions to places far from the inoculation site, i.e., the cervical cord and brain. These results suggest that Cebus apella has limited susceptibility to type 1 poliovirus.

Animals↗
PubMed1986

Experimental Argentine hemorrhagic fever: myocardial involvement in Cebus monkey.

Four Cebus apella monkeys, to test a recently proposed model for testing neurovirulence of Junín virus (JV) strains, were intracerebrally infected with 10(5) LD50 of the XJ clone 3 strain of JV. There were no significant electrocardiographic abnormalities or gross lesions, but all infected monkeys exhibited a varying degree of histologic myocardial lesions including focal lymphoblastic infiltrates, vascular ruptures, and mild interstitial reactive change. One Cebus showed lymphocytic infiltrates in the caudal portion of the A-V node without specific cell involvement. These preliminary results demonstrate cardiac involvement in experimental infection of the Cebus monkey with Junín virus.

Animals↗
PubMed1981

Vaginal adenosis in Cebus apella Monkeys exposed to DES in utero.

Vaginal adenosis comparable to that seen in DES-exposed human newborns exposed to diethylstilbestrol (DES) was observed in 4 (100%) female Cebus apella monkey neonates exposed to DES in utero. Columnar Epithelium lined the vaginal canal and deep crypts in the underlying stroma. The ectocervix was markedly papillary and covered with columnar epithelium that was continuous with the endocervical epithelium. By comparison, the vagina of unexposed newborn and juvenile cebus monkeys up to 15 months of age was filled with a solid core of squamous cells that also covered the cervix and extended into the endocervix. Vaginal adenosis has been produced in mice by neonatal treatment with DES. The mouse model, however, excludes the fetoplacental unit. The cebus monkey provides a model for the investigation of teratogenic effects of intrauterine exposure to DES.

Animals↗
PubMed1998

Degrees of sexual dimorphism in Cebus and other New World monkeys.

Sexual dimorphism in primate species expresses the effects of phylogeny, life history, behavior, and ontogeny. The causes and implications of sexual dimorphism have been studied in several different primates using a variety of morphological databases such as body weight, canine length, and coat color and ornamentation. In addition to these different patterns of dimorphism, the degree to which a species is dimorphic results from a variety of possible causes. In this study we test the general hypothesis that a species highly dimorphic for one size-based index of dimorphism will be equally dimorphic (relative to other species) for other size-based indices. Specifically, the degree and pattern of sexual dimorphism in Cebus and several other New World monkey species is measured using craniometric data as a substitute for the troublesome range of variation in body weight estimates. In general, the rank ordering of species for dimorphism ratios differs considerably across neural vs. non-neural functional domains of the cranium. The relative degree of sexual dimorphism in different functional regions of the cranium is affected by the independent action of natural selection on those regions. Regions of the cranium upon which natural selection is presumed to have acted within a species show greater degrees of dimorphism than do the same regions in closely related taxa. Within Cebus, C. apella is consistently more dimorphic than other Cebus species for facial measurements, but not for neural or body weight measurements. The pattern in C. apella indicates no single best measurement of the degree of dimorphism in a species; rather, the relative degree of dimorphism applies only to the region being measured and may be enhanced by other selective pressures on morphology.

Animals↗
PubMed1976

Genus Cebus Q- and G-band karyotypes and natural hybrids.

The Q- and G-band analyses of Cebus capucinus, Cebus albifrons and Cebus apella are presented. The study is based on the results obtained from 18 specimens of the genus. For almost all of them, their exact locality is known. The data presented include the statement of two natural hybrids from C. capucinus and C. albifrons. On an evolutionary basis our results agree with the taxonomic concepts which postulate more similarity between C. capucinus and C. albifrons than between C. capucinus and C. apella. Furthermore, the comparative study of the Q- and G-band patterns indicates an independent chromosome evolution for C. albifrons and C. apella derived from a common ancestor more similar to C. capucinus.

Animals↗