Conjoined twins in a rhesus monkey (Macaca mulatta)

Conjoined twinning is an extremely rare occurrence among human and nonhuman primates. The current report describes a case of minimally conjoined omphalopagus rhesus monkey twins that were observed in the breeding colony at the California Regional Primate Research Center. The full-term nonviable male twins were morphologically normal and united in the umbilical region, involving the liver, xiphoid, umbilicus, body wall, and skin. The umbilical cords were separate, but closely aligned, within an ensheathing amnion; each cord contained two arteries and a vein. The closely associated cords were centrally inserted on a large bidiscoid placenta. There were no gross or histologic abnormalities in the viscera, with the exception of enlargement of the left central liver lobes, which constituted the area of attachment. The cause of death was attributed to asphyxia and trauma experienced during parturition.     

Alopecia areata in a rhesus monkey (Macaca mulatta)

BACKGROUND: A 14-year-old female rhesus monkey (Macaca mulatta) of Chinese origin has been suffering from alopecia universalis since childhood. METHODS: Recently, the health status of the animal was recorded comprehensively by detailed clinical examination including hematology and serology supplemented by histological and immunohistochemical investigations of skin biopsies and molecular biological techniques to clarify the causes of the persistent hair loss. RESULTS AND CONCLUSIONS: The hairless gene (hr) nonsense mutation was ruled out by polymerase chain reaction and by sequencing of the corresponding gene. Histological examinations revealed a prominent chronic lymphocytic perifolliculitis and folliculitis affecting anagen stage hair follicles as well as miniaturized hair follicles. Immunohistochemistry using the antibodies CD3, CD20 and CD4 confirmed the diagnosis of a T-cell-mediated autoimmune disease resembling alopecia areata universalis in humans.     

Arteriovenous malformation in a rhesus monkey (Macaca mulatta)

A developmental arteriovenous malformation of the right arm was recognized in a 1-year-old rhesus monkey. The diagnosis was based on physical findings, ultrasound, and angiography. Treatment consisting of therapeutic transcatheter embolization using polyvinyl alcohol was performed with partial success. Necropsy revealed a lesion that was limited to the skin and subcutis. An abnormal vascular pattern was present leading to and within the lesion.     

Pott's Paraplegia in a Tuberculous Rhesus Monkey,Macaca mulatta

Thirty-eight young adult Rhesus monkeys (Macaca mulatta) gave negative reactions to four consecutive intrapalpebral tuberculin testings at 2-week intervals. Shortly afterwards, one of six subsequently found to have tuberculosis caused by Myobacterium tuberculosis hominis, suddenly developed dyspnea and paraplegia. Gross and histopathologic examination revealed epidural compression of the spinal cord by excessive granulation tissue originating in the 2nd and 3rd thoracic vertebrae. Neither vertebra exhibited gross structural collapse. One monkey had early generalized tuberculosis and four had pulmonary tuberculosis only. The need for unrelenting vigilance and strict control policies in primate colonies is emphasized.     

Persistent truncus arteriosus in a rhesus monkey (Macaca mulatta)

A 47-day-old female rhesus macaque (Macaca mulatta) was examined because of a severe holosystolic heart murmur (grade 5/6) and signs of congestive heart failure. Results of physical examination, thoracic radiography, and cardiac ultrasonography confirmed an advanced stage of congestive heart failure. Due to the animal's age and clinical signs of disease, a congenital heart defect was suspected. Necropsy revealed a rare congenital heart defect known as persistent (common) truncus arteriosus.     

Sebaceous gland adenoma in a rhesus monkey (Macaca mulatta)

A tumor mass was identified below the shoulder region of a 5-year-old male rhesus monkey (Macaca mulatta). The mass was excised and diagnosed as sebaceous gland adenoma based on the microscopic findings. Morphologically it appeared as an elevated, dome-shaped, circumscribed mass of 3.6 x 2.8 x 3.2 cm in dimension with tan speckled color. Histologically, the tumor was composed of mature, sebaceous cells (sebocytes), basal cells arranged in a mass of irregular shapes and sizes, with a characteristic appearance of poly or multilobular structure. Sebocytes were well differentiated with foamy cytoplasm in the center of the lobules and poorly or undifferentiated densely staining basal cells in the periphery of the lobules. Cellular changes in the adjacent lymph node included hyperplasia of plasma cells, macrophages and lymphoid elements with typical mitosis.     

Adenoviral hepatitis in a SIV-infected rhesus monkey (Macaca mulatta)

BACKGROUND: A 5-year-old female rhesus monkey infected with simian immunodeficiency virus became clinically suspicious with anorexia, increasing weakness and apathy eighty-five weeks after the tonsillar virus inoculation and was euthanised due to a poor prognosis. METHODS AND RESULTS: Postmortal examinations revealed a severe multifocal to coalescing necotizing hepatitis with numerous intranuclear basophilic inclusion bodies. Transmission electron microscopy of the liver resulted in the finding of adenovirus like particles arranged in paracrystalline arrays within the nuclei of hepatocytes.CONCLUSION: The SIV infected rhesus monkey suffered from an adenovirus included necortizing hepatitis, an extremely rare organ manifestation of adenovirus infection in nonhuman primates.     

Juvenile rheumatoid arthritis in a rhesus monkey (Macaca mulatta)

A juvenile rhesus macaque (Macaca mulatta) developed a symmetrical erosive polyarthritis involving both large and small diarthrodial joints. Neither an infectious nor a metabolic etiology could be determined. This case shares many clinical and pathological features with the polyarticular form of human juvenile rheumatoid arthritis.     

Mandibular growth in the rhesus monkey (Macaca mulatta)

Mandibular growth of 42 rhesus monkeys (Macaca mulatta) was analyzed quantitatively and qualitatively. Four groups of animals were defined according to dentitional age (i.e., infant, juvenile, adolescent, young adult). At each age growth was observed for a 24 week period. Since some animals were observed at more than one stage of development, 57 periods of growth were studied. The growth incremental data were collected by superimposing serial cephalograms on mandibular implants. Growth and remodeling of both the skeletal and dento-alveolar components of the rhesus mandible were greatest in the infant monkeys and were less in successive age groups. Posterior relocation of the ramus was noted in all age groups while bone deposition on the anterior and inferior borders of the mandibular body was greatest in the younger animals. The most pronounced dental changes also occurred in the younger animals while the dentitions of the adolescent and adult animals were generally more stable. This study demonstrates that the rate and direction of normal mandibular growth varies with the age of the animal. Furthermore, mandibular growth is quantified at four defined maturational levels to provide a set of values illustrating normal mandibular growth. These values can also be used as control data for experimental studies.     

Naturally occurring melioidosis in a colonized rhesus monkey (Macaca mulatta)

An aged wild-caught male rhesus monkey (Macaca mulatta), maintained in a research facility for 10 years, developed bilateral pelvic limb paralysis without other signs of disease. Unresponsive to therapy, the monkey was killed and necropsied. Chronic inflammation with osteolysis of thoracic vertebrae 10-13 was observed. Pseudomonas pseudomallei was cultured and identified from cerebrospinal fluid obtained at the site of the thoracic lesion. This Gram-negative bacterium can cause infection in animals and man and may remain latent for years before the appearance of clinical signs.     

Menetrier's disease in a rhesus monkey (Macaca mulatta).

Gross and microscopic features closely resembling those found in Menetrier's disease in man are described in a 20-month-old rhesus monkey. The gastric lining was characterized by greatly enlarged rugae caused by mucosal hypertrophy and hyperplasia along with outfolding of the muscularis mucosa and the submucosa. The mucosa and submucosa were infiltrated with inflammatory cells, mainly lymphocytes and plasma cells.     

Seasonal influences on rhesus monkey (Macaca mulatta) behavior

Seasonal differences in the behavior of 2.5- to 4.5-year-old female subjects and male subjects >2.5 years of age were studied in two rhesus monkey groups over a period of 6 years. The frequencies and durations of sexual acts and states were higher during the Fall in Georgia, USA, but were significant only with regard to female partners. Total time in social proximity, scores for proximity by partner without social interaction, nonspecific contact, grooming received, and noncontact forms of aggression with female partners were also higher in the Fall. Although more submission and agonistically ambiguous responses were received from female partners during the Fall, no seasonal pattern prevailed for responses performed. More contact aggression was directed to males in the Spring, and the pattern of agonistic behavior observed cannot be accounted for by males fighting over estrous females. Significantly more play was observed among subjects in the Fall, but the oldest males played more in the Spring. Some patterns, like huddling, were seen more in the Fall, but they may have been due to temperature differences. Seasonal differences in morphology and behavior cannot be attributed to a single variable, like temperature, level of gonadal hormones, or sexual competition, and may reflect a broader adaptation to seasonal variables.     

Corneal biometrics of the rhesus monkey (Macaca mulatta)

Keratometry, retinoscopy, horizontal diameter, and pachymetry were measured in adult and infant rhesus monkeys (Macaca mulatta). The adult monkeys had a mean corneal thickness of 0.47 +/- 0.03 mm (+/- standard deviation), corneal diameters of 10.6 +/- 0.5 mm, keratometry values of 51.90 +/- 1.61 diopters, and subjective refractions of 0.48 +/- 2.36 diopters. Female adult monkeys had smaller corneal diameters by 0.06 mm (P = .02) and steeper corneas by 0.77 diopters (P = .04). Infant female monkeys also had steeper corneas by 2.37 diopters (P = .05). No significant differences were found between right and left eyes in either adult or infant monkeys.     

Sex differences in adolescent rhesus monkey (Macaca mulatta) Behavior

Sex differences in the behavior of 2.5- to 4.5-year-old rhesus monkeys, living in two social groups approximating natural compositions, were studied over a period of 3 years. Both sexes interacted significantly more often with members of their own sex in agonistic and affiliative interactions even when total rates and durations for male and female subjects did not differ. Strong sexual segregation was also seen in proximity, nonspecific contact, and huddling partners. Males were more involved in play and sex than were females and engaged in these activities primarily with other males. Females did more grooming than males, but groomed both male and female partners. Females also appeared to interact with a wider age range of partners than did males. Although total participation in aggressive interactions did not differ between the two sexes, females used more active forms of agonistic expression than did males. These differences in the behavior of adolescent rhesus are hypothesized to lead to social bonding among adolescent males, while females remain bonded to their matri-lines, including younger males and some fully adult males associated with matrilineal relatives. Adolescent males emigrate from their natal groups but retain sociality and bond to males and females in new groups as they become adult. © 1993 Wiley-Liss, Inc.     

Oxytocin is luteolytic in the rhesus monkey (Macaca mulatta)

Oxytocin (10 mi.u./microliter/h) or vehicle (0.5% chlorobutanol in saline, 1 microliter/h) was chronically infused directly into the corpus luteum of normally cyclic rhesus monkeys, by means of an Alzet pump-ovarian cannula system. Infusion of oxytocin (N = 6) or vehicle (N = 5) began 6 days after the preovulatory oestradiol surge, and daily peripheral blood samples were taken. Oxytocin caused a significant (P less than 0.05) decrease in progesterone, beginning 1 day after treatment, and oestradiol after 4 days; progesterone and oestradiol remained significantly depressed until menstruation. However, peripheral LH concentrations remained unchanged. The duration of the luteal phase, menstrual cycle and the onset of menses from the initiation of oxytocin infusion were significantly (P less than 0.01) shorter when compared to those of vehicle-treated controls. These results show that oxytocin can induce functional luteolysis in the primate and supports the hypothesis that oxytocin of luteal origin may play a role in spontaneous luteolysis.     

Late DNA replication in rhesus monkey (Macaca mulatta) chromosomes

A study of the pattern of late DNA replication in rhesus monkey chromosomes showed evident similarities with man. This must be a consequence of the evolutionary conservation of replication patterns in primate chromosomes, as it has been demonstrated in the great apes, in Cebus, and man. However, the pattern of late replication of the allocyclic X chromosome in lymphocytes of female rhesus monkey was identical with the fibroblast pattern in man, and with the pattern found in only 5 to 20% of human lymphocytes.     

Studies of rhesus monkey (Macaca mulatta) hemoglobin.

One hemaglobin was found in the adult rhesus monkey (Macaca mulatta) by the technique of isoelectric focusing. In addition to the adult hemoglobin, one fetal hemaglobin was observed in neonates of the same species. The alpha and non-alpha globins of rhesus monkey hemoglobins showed similar electrophoretic mobilities as those of human hemoglobin A by cellulose acetate membrane electrophoresis. It appeared that the rhesus monkey hemoglobin system is a good model system for the study of human hemoglobin development.