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PubMed1996

Gongylonematiasis in the common marmoset (Callithrix jacchus).

Two cases of gongylonematiasis in common marmosets of two research facilities in Germany are reported. The helminthiasis was transmitted from colony A to colony B by one infected female and within colony B by cockroaches (Blatella germanica). Four of 40 cockroaches examined in colony B were infected with rhabditiform larvae. Clinical signs of disease in the infected animals consisted of intense itching and scratching of the edematous and slightly hyperemic perioral tissues. Histologically the adult helminths lodged predominantly in the mucous membranes of the upper and lower lips; they were less frequently present in the labial cutaneous parts or in the tongue and could not be seen in the esophageal wall, bronchi, or abdominal organs. The helminthic infection probably caused minor to moderate mixed inflammatory infiltrates of the periesophageal connective tissues and intense inflammation of the deep lingual muscular tissues. Lesions of the mucosal membranes of the lips and tongue had predominant accumulations of neutrophilic granulocytes, lymphocytes, and mostly degranulated mast cells with only a few eosinophilic granulocytes. In the cutaneous part of the lips multifocal microabscesses were considered to be secondary lesions from the intense scratching.

Animals↗
PubMed1998

Visuotopic organisation and neuronal response selectivity for direction of motion in visual areas of the caudal temporal lobe of the marmoset monkey (Callithrix jacchus): middle temporal area, middle temporal crescent, and surrounding cortex.

On the basis of extracellular recordings in marmoset monkeys, we report on the organisation of the middle temporal area (MT) and the surrounding middle temporal crescent (MTc). Area MT is approximately 5-mm long and 2-mm wide, whereas the MTc forms a crescent-shaped band of cortex 1-mm wide. Neurones in area MT form a first-order representation of the contralateral hemifield, whereas those in the MTc form a second-order representation with a field discontinuity near the horizontal meridian. The representation of the vertical meridian forms the border between area MT and the MTc. In both areas, the fovea is represented ventrocaudally, and the visual field periphery is represented dorsorostrally. Analysis of single units revealed that 86% of cells in area MT show a strong selectivity for the direction of motion of visual stimuli. The proportion of direction-selective cells in the MTc (53%), whereas lower than that in area MT, is much higher than that observed in most other visual areas. Neurones in the cortex immediately rostral to area MT and the MTc are direction selective, with receptive fields predominantly located in the visual field periphery. In contrast, only a minority of the cells in the cortex ventral to the MTc are direction selective, and their receptive fields emphasise central vision. The results suggest that the MTc is functionally closely related to area MT, and distinct from the areas forming the dorsolateral complex. The MTc may have a role in combining information about motion in the visual field, processed by area MT, with information about stimulus shape, processed by the dorsolateral complex.

Animals↗
PubMed1998

Immunoreactive riboflavin carrier protein concentration during ovulatory cycle in the common marmoset (Callithrix jachhus): role of estrogen.

Common marmoset, a non-human primate, is increasingly being used as a model system in reproductive endocrinology. Marmosets do not menstruate but have normal cycle length of 28 +/- 2 days. The presence of protein immunologically and functionally similar to the well characterized chicken riboflavin carrier protein (cRCP) has been demonstrated in circulation in pregnant marmosets. Marmoset RCP (mRCP) has been partially purified and the molecular weight of the immunoreactive protein is similar to cRCP. The source of RCP in rodents appears to be maternal liver, suggesting thereby that RCP levels could be modulated by changing hormonal pattern that occurs during the cycle. To study the hormonal control of marmoset RCP, immunoreactive RCP levels were monitored during normal cycle. Plasma progesterone was estimated by RIA and mRCP was measured using a heterologous cRCP RIA. When mRCP and progesterone were analysed for a period of 40 days (n = 5) in adult females, very low amount of mRCP was measured during the luteal phase and a single sharp peak was observed during the follicular phase of the cycle. These data suggested that the induction of mRCP was regulated by estrogen. Direct evidence for the role of estrogen in the elaboration of RCP, was the observation that exogenous administration of estradiol 17 B to immature marmosets resulted in a time and dose dependent increase in plasma RCP levels. As early as 24 hr following hormonal administration, a measurable increase in mRCP with a maximum increase, 5-fold over the zero period was seen 3 days following a single administration of estradiol 17 B (5 mg/kg body wt). RCP levels declined thereafter and was indistinguishable by day 7. These studies indicate that the marmoset RCP levels are regulated by estrogen.

Animals↗
PubMed1988

Connections of the primary auditory cortex in the common marmoset, Callithrix jacchus jacchus.

The afferent and efferent connections of the primary auditory cortex (AI) of common marmosets were traced following small injections of wheat germ agglutinin conjugated with horseradish peroxidase (WGA-HRP) made at best frequency (BF)-defined sites in the AI. After the injections the animals remained anesthetized for 15-23 hours; they were then perfused transcardially with fixative and the brains were processed for WGA-HRP reaction product. Examination of the disposition of labelled material revealed the following results. First, patches of terminal labelling, and to a lesser extent retrograde labelling, were found outside the injection site in the ipsilateral cortex rostral and caudal to the AI. Second, the region of the contralateral cortex corresponding to the injection site contained labelled terminals throughout the depth of the cortex; labelled neurons were found in the middle layers. Third, in each experiment a discrete region of the medial geniculate body (MG) contained retrogradely labelled neurons interspersed with anterogradely labelled terminals. These regions had a banded appearance, were found in the dorsal and rostral half of the MG, and shifted in location progressively dorsalward as the injection site BF increased. The presence of projection zones rostral and caudal to the AI of marmosets, and the disposition of the MG sources of projection in relation to BF, are similar to observations made on other New World monkeys. The ipsilateral corticocortical projections confirm electrophysiological evidence suggesting the existence of auditory fields rostral and caudal to the AI. The thalamocortical auditory system of the marmoset appears relatively simple, with a comparatively undifferentiated MG projecting to a cortical auditory system dominated by a large AI.

Animals↗
PubMed1988

Distribution and some projections of cholinergic neurons in the brain of the common marmoset, Callithrix jacchus.

The distribution of choline acetyltransferase-immunoreactive (ChAT-IR) neurons was studied in the brain of the common marmoset by using immunohistochemistry. ChAT-IR neurons were found in the medial septal nucleus, vertical and horizontal limb nuclei of the diagonal band, the nucleus basalis of Meynert, pedunculopontine nucleus and laterodorsal tegmental nucleus, and also in the striatum, habenula, and brainstem cranial nerve motor nuclei. The organization of ChAT-IR neurons in the basal forebrain, midbrain, and pons is consistent with the Ch1-Ch6 nomenclature introduced by Mesulam et al. ('83). The combination of the retrograde transport of HRP-WGA with ChAT immunohistochemistry revealed the distribution of neurons in the Ch4 cell group projecting to the dorsolateral prefrontal cortex. The activity of ChAT was highest in limbic cortical structures, such as the hippocampus, and lowest in association areas of the neocortex. Lesions at various loci in the basal forebrain resulted in differential patterns of ChAT loss in the cortex, which suggests some degree of topographical organization of Ch4 projections to the cortical mantle.

Animals↗
PubMed1979

The retino-geniculo-cortical pathway in Callithrix. II. The geniculo-cortical projection.

After monocular injections of tritiated tracer precursors and transneuronal transport of tritiated compounds, a continuous band of radioactivity in layer IV of striate cortex of Callithrf the crossed and uncrossed retino-cortical pathways. Comparison with the organization of these pathways in other primates suggests that a segregation of the retino-cortical pathways of opposite ocularities into alternating ocular dominance columns in striate cortex has developed independently in the different primate lines. The significance is discussed of the weak labeling of the region of area 17 representing the central retina as compared to the representation of the peripheral retina.

Animals↗
PubMed1977

Topographically organized reciprocal connections between areas 17 and MT (visual area of superior temporal sulcus) in the marmoset Callithrix jacchus.

With the aid of the techniques of tracing axonal pathways by anterograde fiber degeneration, and by anterograde (autoradiography) and retrograde (HRP-histochemistry) axoplasmic transport, it could be shown that area 17 projects in a topographically and visuotopically organized manner onto the temporal visual area MT. The fibers of this association system originate from pyramidal cells in layer IIIc, and from the solitary cells of Meynert; they terminate in layers IV and III of area MT. A correspondingly organized system of countercurrent fibers originates from pyramidal cells in layers III/II and V/VI of area MT and terminates separately in layers VI, IIIc and I of area 17.

Animals↗
PubMed1983

Timing of ovulation and implantation in the common marmoset, Callithrix jacchus, by monitoring of estrogens and 6 beta-hydroxypregnanolone in urine.

Urinary estrogen and 6 beta-hydroxypregnanolone excretions have been determined in female marmosets by means of HPTLC. The levels observed in cycling females during implantation and abortion are reported. Hormone analysis revealed a characteristic pattern showing cyclic fluctuations of estrogens and progesterone. Estrogen metabolites increase during the follicular phase up to 1 microgram/ml, the progesterone metabolite level rises to 1.2 micrograms/ml urine during the luteal phase. Maximum values of both are superimposed in many cases. Ovulatory cycles can be monitored by following estrogen and progesterone metabolites in urine samples. Thus ovulation and the onset of pregnancy can be estimated with a precision of +/- 24 h (or less).

17-alpha-Hydroxypregnenolone↗
PubMed1981

Pharmacologic manipulations of brain catecholamines and the behavior of Callithrix jacchus (marmoset).

In experiment 1, groups of marmosets were injected with 50 - 200 mg/kg L-dopa, 0.5 - 2.0 mg/kg apomorphine (AP), or 0.5 - 5.0 mg/kg methamphetamine. The number of head movements, number of body movements, number of times the tongue was extended, and the time the animal remained in an upright posture were scored during a 90-min period after the injections. L-Dopa and AP induced large dose-dependent increases in body movements and time in upright posture. Furthermore, the smallest dose of AP induced self-destructive behavior. The main effect produced by methamphetamine was a constant turning of the head with the body remaining still. In experiment 2, the marmosets were treated with alpha-methyl-p-tyrosine (AMPT) or haloperidol prior to challenge with AP or methamphetamine. Haloperidol blocked most of the effects of both drugs, while AMPT blocked only methamphetamine effects. In experiment 3, marmosets were injected with increasing doses of haloperidol for 22 days. Upon withdrawal of the neuroleptic, methamphetamine and AP effects were not increased, suggesting absence of supersensitivity of dopaminergic receptors.

Animals↗