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PubMed1996

C-cells of marmosets (Callithrix jacchus).

The localization and fine structure of C-cells of the thyroid glands from 31 marmosets (Callithrix jacchus) of different age groups (newborn to 11 years old) were investigated by electron microscopy and immunomorphology (APAAP, calcitonin). Calcitonin-positive cells were found concentrated in the middle third of the gland. Their localization in the follicular wall or in the interstitial space could not clearly be demonstrated by light microscopy. In adult animals, they were always located within the basal lamina, as revealed by electron microscopy. In newborn animals, their localization was difficult because of the dense cell packing. The fine structure of the C-cells with their 200 nm electron-dense granules corresponded to that of other species. Two cell types could be distinguished: (1) granule-rich cells in the storing phase and (2) cells with fewer granules and well-developed rough endoplasmic reticulum in the synthesis phase. The concentration of C-cells in the middle third of the marmoset thyroid gland renders this species especially suitable for morphological investigations and in vitro experiments.

Aging↗

PubMed1996

Stereology of the myocardium in two species of Callithrix (Callitrichidae, primates).

The majority of studies on cardiac morphology have concentrated on Old World monkeys. Ten marmoset hearts of the genus Callithrix were studied (5 hearts of C. jacchus and 5 of C. penicillata), dissected and fixed in a 10% buffered formaldehyde solution, pH 7.2. Unbiased stereological estimates were obtained from isotropic uniform random sections of the myocardium. For stereological quantification the myocardium was regarded as consisting of cardiac myocytes and interstitium. The volume density (Vv) was determined by point counting. We used the disector method to obtain the numerical density of the cardiac myocytes (Nv[nuclei]). Myocardial stereological differences between the two species of marmoset were not statistically significant. We can therefore determine the pooled Vv[myocyte] and Nv[nuclei] as 68.6% and 41.6% (10(3)/mm3) respectively. The values found for Vv[myocyte] and Nv[nuclei] in the marmoset are respectively about 23.0 and 92.0% greater than those of the baboon, and respectively 57.3 and 45.5% greater than those in man. In contrast, the mean myocyte volume in the marmoset is not significantly different to that of man but is almost 36.0% less than that of the baboon.

Animals↗

PubMed2001

Investigation of the sleep electrocorticogram of the common marmoset (Callithrix jacchus) using radiotelemetry.

OBJECTIVE: To evaluate the use of a totally implantable radiotelemetry system for recording the sleep electrocorticogram (ECoG) of a small new world primate, the common marmoset (Callithrix jacchus) without restraint during data collection. METHODS: Under anaesthesia a telemetry transmitter, which allowed the recording of a single ECoG channel, was implanted intraperitoneally. This system allowed ECoG data to be recorded overnight from animals living in pairs within their habitual laboratory environment over a period of 12 months. Data were subsequently scored using modified Rechtschaffen and Kales criteria (A manual of standardized terminology, techniques and scoring system for sleep stages of human subjects. Los Angeles, UCLA Brain Information Service/Brain Research Institute, 1968) into stages of waking, light sleep, deep sleep and probable rapid eye movement sleep (pREM). Concurrent video recording was used to assist in the categorising of pREM. RESULTS: Results showed that, as in man, the marmoset exhibits sleep cycles with stages alternating between non-REM (deep sleep and light sleep) and pREM sleep throughout the night. In common with other non-human primates the duration of each of the sleep stages was relatively short and punctuated with frequent waking. CONCLUSIONS: These data suggest that sleep in marmosets housed under laboratory conditions (a) can be recorded without restraint and (b) has potential to be used as a model for human sleep.

Animals↗

PubMed1985

Plasmodium brasilianum in the common marmoset Callithrix jacchus.

Chronic quartan malarial infection has been established in the common marmoset (Callithrix jacchus). Plasmodium brasilianum from a douroucouli monkey (Aotus trivirgatus) was used to infect splenectomized twin animals, passed to an intact animal, and then to 4 other intact adults, 2 pairs of twins. In 2 of the 4 latter animals there was continuing patency with parasitaemias of less than or equal to 0.5% parasitized erythrocytes for 30 weeks. The other 2 had lower initial levels of parasitaemia; in 1 of these parasitaemias remained low or subpatent. All marmosets developed lymphocytosis. One animal became ill 30 weeks after infection with anaemia, weight loss and mild proteinurea, the other 3 remained well. Histological examination showed minor changes in the kidneys; spleens of infected animals showed marked follicular hyperplasia and phagocytosis of pigment. The livers showed sinusoidal hypercellularity and pigment deposition and in splenectomized animals, a marked lymphoid follicular hyperplasia in the portal tracts.

Animals↗

PubMed1988

Plasmodium vivax malaria in the common marmoset, Callithrix jacchus: adaptation and host response to infection.

Infection with Plasmodium vivax was established in splenectomized Callithrix jacchus marmosets by inoculation of parasitized blood from Aotus trivirgatus carrying the Vietnam Palo-Alto line of P. vivax. Subsequent blood passage through intact marmosets resulted in higher peak parasitaemias (about 1% of red cells infected) and the loss of stainable Schüffner's dots in infected cells. Primary infections with the adapted line were patent for 74 days or more, and induced both a substantial antibody response, as determined by indirect fluorescence, and some lymphocytosis, but no marked anaemia. Marmosets which had recovered from their primary infection (or in which it was drug-cured) suffered abbreviated patency with low-grade parasitaemia on re-infection.

Animals↗

PubMedDate not supplied

Functional architecture of area 17 in normal and monocularly deprived marmosets (Callithrix jacchus).

The organization of the primary visual cortex (VI) of the common marmoset (Callithrix jacchus) was studied both physiologically and by means of transneuronal labelling of geniculocortical afferents. We addressed the question whether monocular deprivation (MD) could stabilize segregation into ocular dominance (OD) columns, which are not seen in normal adult marmosets but are present in juvenile animals (Spatz, 1979, 1989). Properties of neurons in normal marmosets closely resembled those of other New-World and Old-World monkeys and orderly tangential progressions of preferred orientation were observed. However, in contrast to species that display well-defined OD columns, neurons of layer 4 in V1 of normal adult marmosets received balanced inputs from the two eyes. Early MD (even though followed by prolonged binocular experience into adulthood) resulted in a reduction of cell size in laminae of the lateral geniculate nucleus with input from the deprived eye and a dramatic overall shift in ocular dominance towards the nondeprived eye in the cortex. However, isolated clusters of cells dominated by the deprived eye were found in both layers 4 and 6. Injection of lectin-conjugated horseradish peroxidase (WGA-HRP) into the deprived eye revealed elongated patches of terminal label, about 350 microns wide, in flat-mounted sections through layer 4. Afferent segregation was sharper and more regular in the region of V1 representing parafoveal visual space than in that representing the fovea. Our findings support the notion that all Old-World and New-World monkeys possess the capacity for segregation of geniculocortical afferents into OD columns.

Afferent Pathways↗

PubMedDate not supplied

Topography of ganglion cells and photoreceptors in the retina of a New World monkey: the marmoset Callithrix jacchus.

We studied the anatomical substrates of spatial vision in a New World monkey, the marmoset Callithrix jacchus. This species has good visual acuity and a foveal specialization which is qualitatively similar to that of humans and other Old World primates. We measured the spatial density of retinal ganglion cells and photoreceptors, and calculated the relative numbers of these cell populations. We find that ganglion cells outnumber photoreceptors by between 2.4:1 and 4.2:1 in the fovea. The peak sampling density of ganglion cells is close to 550,000 cells/mm2. This value falls by almost 1000-fold between the fovea and peripheral retina; a value which approaches recent estimates of the centroperipheral ganglion cell gradient for human and macaque monkey retina and primary visual cortex. The marmoset shows a sex-linked polymorphism of color vision: all male and some female marmosets are dichromats. Six of the retinas used in the present study came from animals whose chromatic phenotype was identified in electrophysiological experiments and confirmed by polymerase chain reaction (PCR) amplification of cone opsin encoding genes. One animal was a trichromat and the others were dichromats. Antibodies against short wavelength-sensitive (SWS) cones labeled close to 8% of all cones near the fovea of one dichromat animal, consistent with electrophysiological evidence that the SWS system is present in all marmosets. The topography and spatial density of cone photoreceptors and ganglion cells was similar to that reported for macaque retina, and we found no obvious difference between dichromatic and trichromatic marmoset retinas. These results reinforce the view that the main determinate of primate foveal topography is the requirement for maximal spatial resolution.

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PubMedDate not supplied

The morphology and distribution of horizontal cells in the retina of a New World monkey, the marmoset Callithrix jacchus: a comparison with macaque monkey.

The morphology and distribution of horizontal cells was studied in the retina of a New World monkey, the marmoset, Callithrix jacchus, and compared with that of the Old World macaque monkey. Horizontal cells in macaque and marmoset were either labelled with the carbocyanine dye, DiI, and then photoconverted, or were labelled by intracellular injection with Neurobiotin. The marmoset has two types of horizontal cell, H1 and H2, which have dendritic and axonal morphology similar to their counterparts in Old World monkeys and human. The dendritic-field size of both cell types increases with distance from the fovca. Both types make contact with the vast majority of the cones within their dendritic field. The dendrites of H1 cells in marmoset contact almost twice as many cones as H1 cells in macaque at an equivalent eccentricity. With increasing distance from the fovea, H1 cells make contact with more cones but have, on average, fewer terminal knobs inserted in each cone. The increase in dendritic-field area of H1 cells is balanced by a decrease in spatial density (from 4500 cells/mm2 at 25 deg eccentricity to 1000 cells/mm2 in far peripheral retina), so coverage of the retina remains fairly constant, between 5 and 8. Overall, the results show that the qualitative morphological properties, as well as quantitative population properties of horizontal cells, are common to both New World and Old World primates.

Animals↗

PubMedDate not supplied

Effect of monocular deprivation on NMDAR1 immunostaining in ocular dominance columns of the marmoset Callithrix jacchus.

We previously showed that immunoreactivity to N-Methyl-D-aspartate (NMDA) receptors in primary visual cortex of Callithrix jacchus is regulated by visual activity during the second and third postnatal months (Fonta et al., 1997). The purpose of the present study was to show that the columnar pattern of high and low NMDAR1 immunoreactivity observed in monocularly deprived animals corresponds to ocular dominance columns linked to the nondeprived and deprived eye, respectively. We compared cortical distribution of NMDAR1 receptors and the projection zones of thalamic afferents, revealed by transneuronal transport of tritiated proline, in 2-month-old, either monocularly deprived or control, marmosets. The data show that ocular dominance columns exist in 2-month-old marmosets and that a 2-week monocular deprivation by means of eyelid suture leads to a modification of the thalamo-cortical afferents organization. Experiments of neuronal tracing and immunohistochemistry performed on the same animals demonstrated that cortical domains with decreased NMDAR1 level correspond to the deprived eye columns. These investigations, coupled to the previous results, strongly suggest that the NMDA receptors, regulated by visual activity, are involved in the refining of ocular dominance columns in the primary visual cortex of juvenile marmoset.

Animals↗

PubMedDate not supplied

Long-range interactions in the lateral geniculate nucleus of the New-World monkey, Callithrix jacchus.

Visual stimulation of zones extending beyond the classical receptive field can modulate the contrast gain of neurons in the lateral geniculate nucleus (LGN) of cats, but little is known about the effect of extra-classical visual stimulation on the LGN of primates. Hence, we compare the effect of long-range interactions in parvocellular and magnocellular LGN layers of the marmoset monkey Callithrix jacchus using optimal, incremental spots flashed on the classical receptive field either alone or simultaneously with the shift of a grating (98% contrast; 0.1 cycles/deg) confined to a peripheral annulus (radii: 5-15 deg). The contrast required to drive the response halfway to saturation (c50) of most LGN neurons was raised by remote pattern shifts. The c50 ratio [(shift+spot)/spot] in OFF-center magnocellular neurons was significantly higher than in OFF-center parvocellular neurons. OFF-center magnocellular neurons closer to the fovea (<10 deg eccentricity) tended to have a higher c50 ratio than in more peripheral neurons. A significant drop in visual sensitivity to 25% contrast spots was observed during remote motion: d' fell from 1.8 to 1.4 in parvocellular neurons and from 2.2 to 1.7 in magnocellular neurons. Such long-range interactions produce a reduction in visual sensitivity by changing the gain of the geniculate relay and point to an inhibitory, motion-sensitive extra-classical receptive field in both parvocellular and magnocellular pathways, which may be involved in saccadic suppression and attentional mechanisms in early vision.

Animals↗

PubMedDate not supplied

The distribution of calcium-binding proteins in the lateral geniculate nucleus and visual cortex of a New World monkey, the marmoset, Callithrix jacchus.

Antibodies directed against the calcium-binding proteins, parvalbumin and calbindin, can be used to label distinct neuronal subgroups in the primate visual pathway. We analyzed parvalbumin immunoreactivity (P-IR) and calbindin immunoreactivity (C-IR) in the lateral geniculate nucleus (LGN) and visual cortex of the marmoset, Callithrix jacchus. We compared marmosets which were identified as having dichromatic or trichromatic color vision. Within the LGN, the density of P-IR neurones is highest in the parvocellular and magnocellular laminae, but C-IR neurones are found mainly in the koniocellular division of the LGN, that is, the interlaminar zones and S laminae. Not all interlaminar zone cells are C-IR. In the visual cortex, P-IR neurones are present in all laminae except lamina 1, in areas V1 and V2. Neurones which are strongly C-IR are mainly located in laminae 2 and 3 in V1 and V2. Lightly C-IR neurones are concentrated in lamina 4, and are more numerous in V1 than in V2. Quantitative analysis showed no differences in the density or distribution of IR neurones in either LGN or visual cortex when dichromat and trichromat animals were compared. We conclude that this functional difference is not associated with differences in the neurochemistry of calcium-binding proteins in the primary visual pathways.

Animals↗

PubMed2001

Chemical ecological characteristics of herbivory of Siparuna guianensis seeds by buffy-headed marmosets (Callithrix flaviceps) in the Atlantic Forest of southeastern Brazil.

The buffy-headed marmoset (Callithrix flaviceps) is apparently the only predispersal herbivore of the seeds of Siparuna guianensis at the Caratinga Biological Station in southeastern Brazil. Both the fruit receptacles and the frutioles (seeds) of S. guianensis are relatively rich in nutrients such as carbohydrates, proteins, and lipids, but the receptacles contain high concentrations of benzylisoquinoline alkaloids. The latter presumably act as a qualitative chemical defense, impeding the access of potential predators to the alkaloid-poor frutioles. However, on ripening, the receptacle splits open, exposing the frutioles, which enables C. flaviceps to avoid the plant's chemical defenses effectively. Taking care to avoid contact with the receptacle, the marmosets pluck out the frutioles and ingest the seeds. Qualitative and quantitative changes (in particular a significant reduction in daily ranging) in the marmosets' behavior during the period when S. guianensis frutioles were accessible indicate that this was a preferred plant resource. This is the first record of the consumption of S. guianensis seeds by callitrichine monkeys (which are not known to be systematic seed eaters), despite the fact that both are widely distributed in the Neotropics. It is thus possible that the behavioral strategy observed here is a unique phenomenon resulting from a specific combination of factors, including the abundance of S. guianensis within the study area. The lack of other records may nevertheless be a result of insufficient sampling effort, in which case, the feeding strategies of callitrichines may have an important influence on the reproductive biology of S. guianensis in many areas.

Alkaloids↗

PubMed1999

Intraretinal axon diameter: a single cell analysis in the marmoset (Callithrix jacchus).

We have labelled individual retinal ganglion cells of a New World primate, the common marmoset (Callithrix jacchus) with neurobiotin and then measured axon, soma and dendritic field diameter. A total of 111 cells were analysed (62 parasol cells, 22 midget cells, 16 hedge cells and 11 small bistratified cells). When all retinal ganglion cells were grouped together axon diameter was positively correlated to soma diameter. When analysed according to cell class only midget cells showed a positive correlation between soma size and mean axon diameter. Dendritic field diameter and mean axon diameter of both parasol and midget cells showed significant correlations. Axon diameter is not constant along the intraretinal length of the axon and the rate of change in diameter appears to be related to the cell class and the initial size of the axon. Midget cell axons showed a rapid increase of up to 20% over the first 200 microm in contrast to parasol cell axons which increased more slowly over this distance but then showed a marked increase in diameter of up to 40% over the next 450 microm. However, axon diameter did not remain at these increased diameters but decreased at greater distances from the soma. The degree to which an axon changes its diameter is related to retinal ganglion cell class and the initial size of the axon. We postulate that these variations in intraretinal axon diameter may have a direct influence on conduction velocity and reflect a compensatory mechanism to minimise spatiotemporal dispersion along the visual pathway.

Animals↗

PubMed2001

Experimental allergic encephalomyelitis in the New World monkey Callithrix jacchus.

Models that adequately reflect the complexity of human multiple sclerosis (MS) are needed, especially for preclinical testing of immunomodulatory drugs. Our group has created a unique experimental system in a New World outbred primate, the common marmoset Callithrix jacchus (C. jacchus). Following immunization with myelin, these monkeys develop a chronic, relapsing-remitting form of experimental allergic encephalomyelitis (EAE), which pathologically recapitulates the hallmark features of lesions of human MS. The MS-like lesion in C. jacchus results from a complex immune response against myelin antigens and requires both T cells and pathogenic antibodies. Studies of C. jacchus EAE have permitted the identification of a major target for pathogenic autoantibodies in MS, the myelin/oligodendrocyte glycoprotein. Other advantages of the model include a natural bone-marrow chimerism, which permits T-cell adoptive transfers between siblings, and the possibility of using different antigens to produce either inflammatory or demyelinating phenotypes of EAE. Despite their small size, sequential in vivo imaging and immunological studies are possible in these monkeys, and have been used to monitor efficacy in preclinical trials. Due to close phylogeny and high homology of immune and nervous system genes with humans, this model should fast-track the development of novel therapeutics for MS.

Animals↗

PubMed2002

Neonatal behavioral scoring of common marmosets (Callithrix jacchus): relation to physical condition and survival.

A seven-task behavioral test was performed on 86 common marmoset (Callithrix jacchus) infants, 24-36 h following birth. This report describes the test outcome and its relation to physical condition and survival of the infants. The percentage of infants receiving a perfect score on a given task ranged from 30.6 (rooting) to 70.6% (grasping). Heavier infants were more likely to have perfect scores for crawling (F=4.20, P=0.044) and infants with a longer knee-heel length tended to be more likely to have a perfect grasping score (F=3.63, P=0.06). While the modal score was a perfect score for most individual tasks, the modal number of total perfect scores that a given infant received was 3-4 and only 4.7% of infants received perfect scores on all seven tasks. These results suggest that this group of behavioral tasks will produce a variable response within a population of neonates. While no individual behavioral score predicted survival during week 1, the number of perfect scores across all tasks was predictive of survival outcome; infants with a higher total number of perfect scores were more likely to survive (F=6.02, P=0.018). When all combinations of tests were compared, the best predictor of survival was outcome on four of the seven tests, all related to motor skills (F=7.46, P=0.009).

Animals↗

PubMed2000

The effect of dopamine depletion from the caudate nucleus of the common marmoset (Callithrix jacchus) on tests of prefrontal cognitive function.

This study examined the effects of depletion of dopamine from the caudate nucleus of the common marmoset (Callithrix jacchus), on tasks sensitive to prefrontal damage (attentional set-shifting and spatial delayed response). There was a marked impairment in performance on the spatial delayed response task, but performance on the attentional set-shifting task was relatively preserved except for an impairment in re-engagement of a previously relevant perceptual dimension. This pattern of impairment is distinct from that seen after excitotoxic lesions of the prefrontal cortex and in patients with Parkinson's disease. Though it is not possible to identify specific cognitive functions that are independent of dopaminergic modulation of the caudate nucleus, due to the partial nature of the lesion, the results do provide insight into those cognitive processes that appear most dependent on caudate dopamine.

Animals↗

PubMed1993

Effects of sex steroids on maternal motivation in the common marmoset (Callithrix jacchus): development and application of an operant system with maternal reinforcement.

We developed an operant paradigm for measuring effects of reproductive steroids on maternal motivation in common marmosets (Callithrix jacchus). Conditioned response regulated females' exposure to maternal reinforcement. Nulliparous females (n = 15) with experience with infants in social groups were subjects. The paradigm was validated by examining (a) effects of reinforcing stimuli on affective behavior in a nonoperant paradigm, (b) responsiveness of operant performance to changes in reinforcing stimuli and reinforcement schedule, (c) changes in operant responding due to omission of reinforcement, and (d) relation between operant responding and species-typical maternal behavior. In pregnant females, (n = 4), frequency of bar pressing and estradiol:progesterone ratio were maximal just before birth. Nonpregnant females (n = 3) treated with progesterone and estradiol to mimic late-pregnancy steroid profiles showed increased operant maternal behavior.

Acoustic Stimulation↗

PubMed1994

Marmoset (Callithrix jacchus jacchus) spatial memory in a foraging task: win-stay versus win-shift strategies.

The spatial memory of common marmosets (Callithrix jacchus jacchus) was explored in 3 experiments with a simulated foraging task. In Experiment 1, individual monkeys foraged among 8 baited food sites. They appeared to use spatial memory to accurately avoid revisiting previously depleted sites. There was no difference in accuracy between the adult monkeys and a juvenile monkey tested on the same task. In Experiment 2, a win-stay paradigm was used. The adult monkey subject very accurately remembered locations that had previously contained food. The monkey tended to visit adjacent correct sites when retrieving food and thus minimized the total distance travelled. In Experiment 3, a win-shift paradigm was used with 2 adult monkeys. Although both monkeys performed at above-chance levels of accuracy on the win-shift task, they made many errors. These results suggest that marmosets may prefer tasks that require a win-stay strategy.

Animals↗