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PubMed1999

Sexual behavior and extragroup copulations in a wild population of common marmosets (Callithrix jacchus).

Sexual behavior and mating patterns are described for 3 free-ranging groups of common marmosets living in a coastal forest in northeastern Brazil. Each group contained 2 breeding females. Within groups, sexual behavior was generally restricted to breeding females and a single behaviorally dominant male. Of 101 mounts and copulations, 24 involved pairings of individuals from 2 different groups. Extragroup sexual behavior was performed by both breeding and nonbreeding group members, and 65% of all adults mounted or copulated with an extragroup individual at least once. Sexual behavior occurred throughout the female reproductive cycle but was significantly more frequent during an 11-day 'conception period'. Thus, while female marmosets show no physical signs of estrus, both males and females likely do have some information about the timing of ovulation. Mating patterns in this population included both polygyny and monogamy and varied between groups and over time.

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PubMed2002

Central olfactory connections in the microsmatic marmoset monkey (Callithrix jacchus).

The mammalian primary olfactory system consists of a set of different telencephalic structures, including paleo-, archi-, periarchi- and mesocortical components. We present the first characterisation of the normal and connectional anatomy of the primary olfactory cortex of the common marmoset, a microsmatic simian species increasingly used in primate research. The centrifugal and centripetal bulbar projections were determined by injections of the anterograde and retrograde tracer wheat germ agglutinin-conjugated horseradish peroxidase and fluorescent dyes into the ipsilateral main olfactory bulb. The efferent projections of the marmoset bulb are organised entirely ipsilaterally and are established via a rudimentary medial olfactory tract and the dominant lateral olfactory tract. Target areas are the anterior olfactory nucleus, the entire prepiriform cortex, ventral tenia tecta, periamygdaloid cortex and the rostral part of the entorhinal cortex. The bulbar axons predominantly terminate in the outer part of layer I. The anterior olfactory nucleus receives a weak additional input within layer II and III, which is not found in macrosmatic rodents. Further anterograde labelling was found in the endopiriform nucleus deep under the prepiriform cortex and within an anterolateral strip of the olfactory tubercle. However, control injections into the olfactory tubercle suggest that the marmoset olfactory tubercle receives a bisynaptic olfactory input only. Retrograde labelling after bulb injections revealed that, except for the olfactory tubercle, all primary olfactory cortices contributed to an ipsilateral bulbopetal feedback projection. Like in rodents, the only bulbopetal projection organised bilaterally in the marmoset is maintained by the anterior olfactory nucleus. With few exceptions, the projections of the marmoset olfactory brain are organised similarly to that of the macaque monkey or those of macrosmatic species.

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PubMedDate not supplied

Hawk calls elicit alarm and defensive reactions in captive Geoffroy's marmosets (Callithrix geoffroyi).

Most descriptions of callitrichid antipredator behavior have come from observations of visual encounters with predators, but there is also anecdotal evidence suggesting that callitrichids may use auditory cues associated with raptors for the early detection of potential danger. In the present study, Geoffroy's marmosets consistently reacted to the tape-recorded calls of a red-tailed hawk (Buteo jamaicensis) with high-intensity antipredator behaviors. Compared to the taped calls of a raven (Corvus corax) and the taped sound of a power drill, the hawk calls elicited more startle reactions, more alarm calls, longer freeze times, increased use of safe areas of their enclosure and greater disruption in ongoing behavior. Once in a relatively safe location in the enclosure, the marmosets visually monitored the site of origin of the calls for 10 min and minimized locomotion for 30 min, but resumed baseline levels of other activities that had been disrupted by the hawk calls. Marmosets may use the auditory cues associated with predators for early detection, and subsequent avoidance, of a potential predator in the vicinity.

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PubMed1985

An allometric study of hippocampal components. A comparative study of the brains of the European hedgehog (Erinaceus europaeus), the tree shrew (Tupaia glis), and the marmoset monkey (Callithrix jacchus).

Brains of western European hedgehogs, common tree shrews and common marmosets were perfused and stained according to Timm's method. The volumes of hippocampal components were determined with semiautomated quantitative techniques and compared by allometric methods. The results support previous findings that the size of the hippocampus in marmosets and tree shrews is about twice that of the hippocampus of the European hedgehogs of the same body weight. Three hippocampal substructures account for most of this progression. These are the hilus, the deep zone of the molecular layer of the area dentata, and CA1 (especially the cellular layer) of Ammon's horn.

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PubMed1980

Natural antibodies to EBV-VCA antigens in common marmosets (Callithrix jacchus) and response after EBV inoculation.

Healthy common marmosets from two separate colonies, one in England and one in France, were found to have antibodies cross-reacting with Epstein-Barr virus structural antigens (EBV-VCA). All seropositive animals were at least 2 years old. Experimental EBV infection of marmosets of different ages led to seroconversion of inoculated weanlings. Adult animals either developed antibody for the first time or showed an increase in their existing titers. Both control and infected animals developed a progressive interstitial nephritis. The lymphocytic infiltration was more extensive, diffuse and immature in appearance in inoculated animals, but no definite evidence of lymphoproliferative disease or lymphoma was found.

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PubMed1983

Body weight changes throughout pregnancy in the common marmoset Callithrix jacchus.

Adult female common marmosets were weighed weekly for periods of 6-30 months. Of 27 animals, 25 were pregnant at some stage of the investigation. Patterns of body weight change throughout singleton, twin and triplet pregnancies were obtained and compared. Maternal weight increase was dependent on the number of young in utero; however, little or no change in weight was observed during the first 13 weeks of gestation, irrespective of the number of offspring delivered subsequently. The overall maternal:fetal body weight ratio was 1.00:0.21, ranging from 1.00:0.11 for singleton to 1.00:0.26 for triplet pregnancies. Lactation had little or no effect on maternal body weight during the first 4 weeks postpartum.

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PubMed1984

Reproductive status of adult daughters in family groups of common marmosets (Callithrix jacchus jacchus).

Urine samples were collected from 6 pubertal female common marmosets at approximately 3-day intervals over a period of 3-7 months. All 6 females were the eldest daughters in their family groups. 3 of these females were subsequently removed from their families and sampled in isolation for another 2-3 months. Levels of urinary pregnanediol-3 alpha-glucuronide were measured by radioimmunoassay in order to establish whether these females showed ovarian cyclicity. No cyclical fluctuations in the levels of pregnanediol were observed in the females housed with their families even though the females were of a reproductively mature age. Cyclicity was quickly established (within 18-22 days) when the females were removed from the family. These results are discussed in the light of similar recent investigations on callitrichid reproduction and the behavioural implications are considered.

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PubMed1990

Medial hypothalamic lesions and sexual receptivity in the female common marmoset (Callithrix jacchus).

Medial hypothalamic lesions cause major deficits in sexual receptivity in a variety of mammalian species. Effects of such lesions upon sexual receptivity in female primates have not been investigated. Two experiments are described in which thermal lesions were made in the hypothalamus in 11 ovariectomized or ovariectomized/adrenalectomized, oestradiol-treated common marmosets. Proceptivity (sexual initiating behaviour) was reduced or abolished by lesions in the dorsomedial or ventromedial hypothalamus. Sexual receptivity was unaffected except in 3 females in which damage to the ventromedial area was associated with a 25-42% increase in terminations of males' mounts. However, this effect was reversed by treating females with oestradiol. Therefore, medial hypothalamic lesions have pronounced effects upon proceptivity in the marmoset, whereas effects upon receptivity are much less pronounced or absent. These results are discussed in relation to the evolution of the hormonal control of receptivity in anthropoid primates as compared to other mammals.

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