Somatic chromosomes of squirrel monkey (Saimiri sciureus)

The chromosome complement of 2 male and 15 female adult squirrel monkeys (Saimiri sciureus) have been studied in peripheral blood and kidney cultures and bone marrow preparations. The diploid chromosome number is 44. Six of the chromosome pairs are metacentric (isobrachial), 9 pairs submetacentric (heterobrachial) and the remaining 6 pairs are acrocentric (cephalobrachial). The X chromosome is the longest submetacentric (heterobrachial), ranking 5 in order of decreasing size. The Y chromosome is the smallest acrocentric (cephalobrachial) of the complement.A female and male karyotype is presented.Supported, in part, by Grant HDO 1952-03 from the United States Public Health Service.     

Hepatocellular carcinoma in a squirrel monkey (Saimiri sciureus)

Abstract: A well-differentiated hepatocellular carcinoma of the liver was diagnosed in a female squirrel monkey. The lesion showed trabecular, solid and glandular features that are characteristics of malignant liver tumours.     

Tonic immobility in the squirrel monkey (Saimiri sciureus)

Tonic immobility and several accompanying behavioral changes were examined in the squirrel monkey (Saimiri sciureus). It was found that either the occurrence of a loud noise immediately before induction or the presence of a stuffed Cooper's hawk increased the duration of immobility in some subjects. Subspecies differences in durations of immobility were also found. The number of inductions required to produce immobility in squirrel monkeys were unusually large, and were negatively correlated with duration of the response. Behavioral variables accompanying tonic immobility showed qualitative differences when compared to what is known concerning their relation to immobility in other species. The findings support the belief that tonic immobility evolved as a predator defense in squirrel monkeys or one of their ancestors, but suggest that it no longer plays an active role in their survival.     

Lipid composition of squirrel monkey (Saimiri sciureus) saliva

The content and composition of lipids in saliva of healthy caries-free squirrel monkeys were investigated. The dialyzed and lyophilized saliva on extraction with chloroform/methanol yielded 8.0 +/- 0.9 mg of lipids/100 ml of saliva. Following fractionation on silicic acid column, 30.9% of lipids were found in the neutral lipid fraction, 58.8% in the glycolipid fraction, and 10.3% in the phospholipid fraction. The neutral lipids exhibited high content of free fatty acids (58.8%) and triglycerides (23.3%), the glycolipids consisted mainly of neutral and sulfated glyceroglucolipids (95%), while the phospholipids were rich in sphingomyelin and phosphatidylcholine. The results show that squirrel monkey saliva, while displaying lipid content similar to that of caries-susceptible humans, contains 50% less lipids than saliva of periodontal disease-prone marmoset.     

The brachial plexus in the squirrel monkey (Saimiri sciureus)

Based on the statistical data obtained from 37 squirrel monkeys, the standard type of the brachial plexus was determined. Each of the superior (C6, normally also C5), middle (C7), and inferior (C8 and T1, rarely with rudimentary T2) trunks gives off the anterior and posterior divisions. The lateral cord composed of the superior and the middle anterior divisions usually breaks up immediately into the musculocutaneous nerve and the lateral root of the median nerve. The medial cord (generally the peripheral extension of the inferior anterior division itself) terminates in the ulnar nerve and in the medial root of the median nerve. The dorsal cord formed by the union of the 3 posterior divisons extends peripherally as the radial nerve; the axillary nerve arises before the union of the 3 posterior divisons is completed. The frequently encountered aberrant connecting branches, the musculocutaneous nerve tending to separate from the plexus, and the long lateral root of the median nerve characterize the feature of the plexus.The data were compared with previous findings about the plexus of other primates.This investigation was conducted during the tenure of a postdoctoral fellowship in the Department of Anatomy, UCLA School of Medicine, Los Angeles, California, U.S.A.     

Genetically determined antigens of squirrel monkey (Saimiri sciureus) IgG

Alloantigens of squirrel monkey (Saimiri sciureus) IgG were studied using alloantisera prepared by cross-immunizations among four subspecies. The results demonstrated the occurrence of IgG antigenic polymorphism. Three distinct Fd fragment allotypes were detected. Greater alloantigenic complexity occurred among Colombian and Peruvian squirrel monkeys, which occupy the more central regions of the geographic range; Bolivian and Guyanan monkeys, which occupy the extremes of the range, expressed less alloantigenic complexity.     

Carcinosarcoma of the maxilla in a squirrel monkey (Saimiri sciureus)

We present the first, to our knowledge, described case of carcinosarcoma of the maxilla in a squirrel monkey. Carcinosarcomas are rare tumors of the upper aerodigestive tract, and consist of carcinomatous and sarcomatous tissue. Histologic analysis revealed a neoplasm composed of an adenocarcinomatous component (epithelial element) and a mesenchymal component (sarcomatous element). Metastatic growth was documented in the lung tissue and the submandibular lymph node. The histolopathologic findings, the pattern of metastasis, and the clinical progression closely resembled those of carcinosarcoma involving salivary glands in humans.     

Malignant lymphoma in a squirrel monkey (Saimiri sciureus).

A juvenile male Saimiri sciureus died of a tumor diagnosed as a histiocytic type of malignant lymphoma. The neoplasm presented as a thoracic mass occupying the posterior mediastinum and infiltrating the contiguous structures without involving distant nodes, the liver or spleen. The tumor tissue consisted of sheets or poorly defined clusters of fairly large cells with a vesicular nucleus and a variably abundant cytoplasm. The tumor cells were laid out in a poorly developed stroma of fine argyrophilic fibers. This is the first report of a spontaneous malignant lymphoma in a primate of this species. The speculation is put forth that the reported tumor is probably the first known example of the long sought after correlate of squirrel monkeys to Burkitt lymphoma in man.     

Retrobulbar primitive neuroectodermal tumor in a squirrel monkey (Saimiri sciureus)

Background A 2.8‐year‐old female captive‐bred common squirrel monkey (Saimiri sciureus) showed exophthalmos of the right eye, and the eye was surgically enucleated. A tumor mass was found in the eye. Methods Formalin‐fixed tumor samples were examined histopathologically and immunohistochemically for diagnosis. Results The retrobulbar tumor mass adhered to the sclera and infiltrated the choroid. Histopathologically, tumor cells were pleomorphic, arranged in a sheet pattern, and mimicked primitive neuroectodermal cells. The tumor cells were strongly positive for precursor neuronal cell markers (beta III tubulin, neuron‐specific enolase, vimentin, nestin, doublecortin, oligo2, and S‐100), but negative for mature cell markers (cytokeratin, neurofilament, and glial fibrillary acidic protein) and a retinoblastoma marker (rhodopsin). Conclusions This is the first reported case for the retrobulbar location of primitive neuroectodermal tumor in non‐human primates.     

Spontaneous cryptococcosis of a squirrel monkey (Saimiri sciureus) in French Guyana

An old female squirrel monkey (Saimiri sciureus) with a tumor-like growth of the lower jaw died in shock after 2 months of illness. Histological studies of different tissue samples demonstrated that the pathological agent was Cryptococcus. Multiple foci of fungus existed in the thoracic cavity with essentially pulmonary and glandular localizations.     

The first report of peritoneal tetrathyridiosis in squirrel monkey (Saimiri sciureus)

This report describes a case of peritoneal larval cestodiasis caused by tetrathyridia of Mesocestoides sp. in an adult female squirrel monkey. The monkey had lived in a zoological garden in Japan and had a clinical history of wasting. At necropsy, numerous whitish oval masses were found in the liver and peritoneal cavity. These masses contained larval cestodes. Morphological observation and molecular analyses of the mitochondrial 12S ribosomal RNA gene and cytochrome c oxidase subunit 1 gene sequences allowed us to identify the larva as the tetrathyridium of Mesocestoides sp. This is the first report of Mesocestoides larvae in a squirrel monkey in Japan.