Adductor muscles of the thigh of crab-eating monkeys (Macaca fascicularis)

On the basis of 44 hindlimbs of 14 male and 14 female crab-eating monkeys (Macaca fascicularis), the morphology of the adductor muscles of the thigh was described and some functional indices were calculated. The results obtained from this study agreed generally with those of otherMacaca species reported by various authors. For the classification and nomenclature of the adductors, the criteria proposed byUhlmann (1967, 1968) was well adapted to the crab-eating monkey. The adductors comprise the m. gracilis, m. pectineus, m. adductor longus, pars longa and pars brevis of m. adductor brevis, pars lata and pars minima of m. adductor magnus and m. obturatorius externus. In males, the adductors are generally inserted further down the femur, and the insertions of pars brevis of the m. adductor brevis and pars minima of the m. adductor magnus have longer attachments to the femur than in females. The arrangement of each adductor muscle and of each fasciculus of a thigh muscle may invoke a principle of organization.     

Flexor muscles of the thigh of crab-eating monkeys (Macaca fascicularis)

On the basis of 28 hindlimbs of nine male and eight female crab-eating monkeys (Macaca fascicularis), the morphology of the flexor muscles of the thigh are described and some functional indices calculated, and these results are compared with those of some other primates. The results obtained from this study agreed generally with those of otherMacaca species. In general, the functional indices devised byStern (1971) did not show any significant differences between the right and left hindlimbs or between male and female monkeys, except for the index expressing the level of insertion of the m. biceps femoris on the tibia. The m. biceps femoris inserts further down the leg in females than in males.     

The extensor and peroneal muscles of the crab-eating monkey (Macaca fascicularis)

On the basis of 60 hindlimbs of 30 crab-eating monkeys (Macaca fascicularis) of each sex, the morphology of the crural extensor and the peroneal group of leg muscles is described and some functional indices are calculated. For the attachments and measurements of the muscles, the results obtained in this study generally agreed with those of otherMacaca species. The crural extensor has minor differences. Some anomalous modes of insertion are observed in the peroneal group. These results indicate the phyletically labile state of the peronei in the crab-eating monkey.     

Ovum recovery and in vitro fertilization in crab-eating monkeys (Macaca fascicularis)

A total of 301 oocytes were recovered from crab-eating monkeys and subjected to insemination in vitro resulting in two fertilized ova. Sixteen monkeys in 24 cycles received 37.5 IU of hMG daily from the second day of the menstrual cycle for 7 to 10 days. Oocytes were recovered under laparotomy at 20 to 49 hr after administration of 1,000–1,500 IU of hCG. The maturation rate of the recovered oocytes was 24.2% as judged from morphological criteria under the light microscope. With additional maturation culture, the rate increased to 36.2%. The matured oocytes were inseminated at 3 to 4 hr after aspiration using homologous spermatozoa which had been capacitated in vitro. Two oocytes were judged as being fertilized based on the presence of 3 and 5 pronuclei, respectively, when examined 12 hr after the insemination. This is the first report of in vitro fertilized ova in nonhuman primates in Japan.     

Age assessment in infant crab-eating monkeys (Macaca fascicularis) based on tooth development

Tooth development was studied in 13 Macaca fascicularis monkeys with known dates of birth. Regular intra-oral examination was carried out and standardized lateral radiographs were collected from 27 until 150 weeks of age under general anaesthesia.
Three stages of tooth development were determined radiographically: onset of crypt formation, onset of mineralization, and crown completion. A fourth stage, the emergence, was determined clinically. Developmental stages were recorded for six mandibular and five maxillary teeth.
The ages of emergence of the permanent teeth and the developmental stages of the third molars showed the largest variation. A significant sex difference with earlier maturation in males was found for the start of crypt formation of the maxillary permanent canines and the maxillary second premolars, and for the start of mineralization of the maxillary permanent canines.
The data provide a tool by which chronological age can be assessed of Macaca fascicularis monkeys between 30 and 80 weeks of age. Owing to an interphase of about one year without significant developmental features in the dentition, age assessment based on tooth development cannot be performed from about 80 to 130 weeks of age. Age assessments are possible for the period between 130 and 150 weeks of age. However, in this period the reliability of the data is lower due to larger time intervals and standard deviations.     

The reproductive cycle of the crab-eating macaque (Macaca fascicularis)

Characteristic changes in the menstrual cycle of the crab-eating macaque were evaluated. Cyclical changes in type and abundance of exfoliated cells in vaginal smears as well as the ferning pattern of cervical mucus were observed. These indices were useful in predicting approximate ovulation time. The cyclical changes in sexual skin swelling and/or coloration were detected only in adolescent females. Micro-sections from ovaries of autopsied animals revealed large Graafian follicle formations often rupturing by day fourteen of the cycle. Length of the menstrual cycle ranged from 26–38 days with a modal value of 28 days.This research has been supported by Ford Foundation Grant No. 710-0287.     

Morphology of diaphragm in the crab-eating monkey (Macaca fascicularis)

The diaphragm was studied in 30 adult crab-eating monkeys (Macaca fascicularis). The muscular bundle of the lumber part was derived from the tendinous origin, which attached to the anterior surface of the lumbar vertebra and intervertebral disc. The upper margin of the origin was at the one third of the second lumbar vertebra in both sides. The lower margin of the right and left tendons extend to lower one third and upper one third of the third lumbar vertebra, respectively. In 22 cases (73.3%) out of 30 specimens, some muscular bundles arose from the right crus with the collagenous sheath. They ran across the ventral aspect of the aortic hiatus and bounded the esophageal hiatus at the left side. The muscular fibers, which bound the esophageal hiatus at the right and left, are innervated by ipsilateral phrenic nerve. In four cases, the “Hilfsmuskel” after Treitz was observed. It arose from the connective tissue around the coeliac artery.     

Multiple alpha-globin genes in crab-eating macaques (Macaca fascicularis)

Alpha-globin genes in crab-eating macaques were found to be triplicated at high frequencies according to restriction-enzyme comparisons. The frequencies of triplicated alpha-globin genes in macaques originally from Malaysia and Indonesia were 0.432 and 0.275, respectively, while no triplication was found in individuals from either the Philippines or northern and central Thailand. Quadruplicated alpha-globin genes were also observed, at frequencies of 0.045 (Malaysia), 0.075 (Indonesia), and 0.021 (the Philippines). A single locus was detected in only one of 40 chromosomes from Indonesia (frequency 0.025).     

Hazard rates and causes of death in a captive group of crab-eating monkeys (Macaca fascicularis)

In an attempt to examine possible associations between stages of agespecific mortality and various causes of death, vital records of 159 male and 192 female crab-eating monkeys (Macaca fascicularis), housed as a single group, were analyzed. Survival and hazard rates associated with each of five distinct categories of causes of death were estimated for males and females, using the nonparametric kernel method. The obtained overall survival and hazard functions were similar to those reported previously for rhesus monkeys. Among two stages identified in age-specific mortality, the first stage, characterized by rapidly decreasing hazard rates up to about 1.5–2 years of age, was discriminated by the occurrence of deaths due to unfitness for postnatal life. The second stage lasted up to the age of 10–15 years and was largely characterized by a high incidence of violent deaths. The respective hazard rates in males and females attained peaks during the early reproductive period of life and markedly decreased thereafter. This pattern was interpreted to indicate that second stage mortality is unlikely related to senescence, but rather, seems to depend on extrinsic environmental factors. Thus, when considering overall hazard rates in Macaca fascicularis, the onset of senescence, as a result of the specific aspects of simian reproduction, may be hidden from view, and mortality due to aging may only be appreciable after 10 to 15 years of age. © 1993 Wiley-Liss, Inc.     

The effect of female proximity and social interaction on the menstrual cycle of crab-eating monkeys (Macaca fascicularis)

Twelve adult female crab-eating monkeys (Macaca fascicularis) were placed in six pairs of adjacent cages, allowing physical contact between members of these experimental pairs. Twelve additional females remained singly caged (no physical contact allowed) and served as six control “pairs.” In both experimental and control pairs, one member had a history of regular menstrual cycles, whereas the other tended to have cycles that were unusually long and/or irregular. Over a six-month period, menses and amount of vaginal secretion were recorded daily for all subjects, and the behavior of experimental pairs was sampled three times per week. During the course of the study, the irregular experimental subjects began to exhibit menstrual cycles of near normal length although there was no apparent trend to synchronize cycles. Irregular controls continued to show cycles that were abnormally long. Vaginal secretions tended to increase in all regularly cycling animals during days 9–15 (peak day 11) or reverse days 21–16 of the cycle, consistent with the estimated time of ovulation. Analysis of behavior indicated that irregularly cycling subjects inspected the genitalia of their regularly cycling cagemates at a significantly higher frequency than the converse (F=12.61,p<.005), particularly during the follicular phase (F=3.39,p<.07). These results suggest that close physical contact may serve to transmit chemical and/or hormonal cues that can normalize the menstrual cycle of crab-eating monkeys.     

Population genetics of crab-eating macaques (Macaca fascicularis) on the island of mauritius

Protein polymorphisms of the crab-eating macaque (Macaca fascicularis) on the island of Mauritius in the southwest Indian Ocean were examined electrophoretically for 201 blood samples. All of the variant types detected were those found previously in the Asian populations. Genetic variability of the island population was estimated to be P_poly = 16% and H = 6.5%, which was lower than that of the Asian populations. A tendency that a small number of loci were highly polymorphic was observed. These results may reflect the establishment of the island population from a small number of introduced ancestors, or the existence of the bottleneck effect. For the origin of the Mauritian monkeys, comparison of electrophoretic variants suggested that they originated from the Malay Peninsula or the Greater Sunda Islands, especially from Java. Though the homozygous individuals exceeded in number as a whole, a significant subdivision was not detected in the population. © 1993 Wiley-Liss, Inc.     

Peripalpebral folds and entropion in a male crab-eating macaque (Macaca fascicularis)

Multiple peripalpebral folds were the cause of severe bilateral blepharospasm and epiphora in a male Macaca fascicularis. The inner-most fold resulted in entropion and irritative keratitis. The condition was corrected surgically.     

Insular amyloidosis and diabetes mellitus in a crab-eating macaque (Macaca fascicularis)

Clinicopathologic examination of a crab-eating macaque (Macaca fascicularis) with chronic weight loss and bilateral cataracts revealed high fasting serum glucose, glucosuria and hypercholesterolemia. Clinical signs were eliminated by treatment once a day with isophane insulin suspension. Extensive insular amyloidosis was found microscopically sixty days later.     

Cryopreservation of spermatozoa from cynomolgus monkeys (Macaca fascicularis)

Three egg-yolk diluents, which have been used successfully in cryopreservation of human spermatozoa, were compared for their ability to protect macaque semen against cryodamage. TEST (Tes + Tris + egg yolk), TEST with 20% skim milk (TSM), and egg yolk-citrate (EYC), each with 3 or 5% glycerol were compared using 12 ejaculates from 6 male cynomolgus macaques. Computer-aided analysis of sperm motion was used to determine the percentage motility (%M), curvilinear velocity (VCL), and linearity (LIN) of spermatozoa after thawing. The supravital stain Hoechst 33258 and a fluoresceinated pea lectin were used to determine the % of viable spermatozoa with intact acrosomes. TSM and TEST were superior to EYC in terms of % M and of % viable, acrosome-intact spermatozoa. TSM and TEST produced equivalent VCL and LIN values, while EYC had clearly reduced VCL and LIN. There were no interactions between diluent and glycerol level. The 3% glycerol level gave superior results to 5% glycerol for %M. EYC, which is widely used for cryopreservation of human spermatozoa, was not suitable for cynomolgus monkey semen. Artificial insemination with semen cryopreserved in TSM resulted in a healthy, full-term infant.     

Spontaneous diabetes mellitus in cynomolgus monkeys (Macaca fascicularis)

Glucose tolerance tests were performed with fourteen cynomolgus monkeys. They were divided into two groups with regard to the serum glucose level at the time of routine health-examination. Nine of them had normal glucose level (below 123 mg/dl, the normal group) and the other five monkeys exhibited hyperglycemia (the abnormal group). Fifty per cent glucose solution was administered into the saphenous vein at a dose of 4 ml/head. Blood samples were taken just before and 5, 10, 20, 30, 60 and 120 minutes after the glucose administration. K-value (K = 0.693/t 1/2 X 100) as the decreasing rate of serum glucose during from 5 to 60 minutes after the administration was calculated. Average K-value for eight monkeys of the normal group was 3.12 +/- 0.48. Both immunoreactive insulin level (IRI) and C-peptide immunoreactivity (CPR) increased just after the glucose administration and began to decrease 5 to 30 minutes after the administration in all the eight animals. Remaining one animal (No. 009) of the normal group showed 1.03 in K-value. For the abnormal group, K-value averaged 0.75 +/- 0.25. IRI was slightly higher in this group than in the 8 monkeys of the normal group. Furthermore, the abnormal group did not show any definite change of a certain trend in IRI and CPR. In conclusion, the former 8 monkeys were judged to be normal in the function of pancreatic beta-cells, and the latter 5 monkeys and No. 009 monkey were judged to be suffering from type II (noninsulin dependent) diabetes mellitus at different stages of the disease.     

Blood groups of crab-eating macaques (Macaca fascicularis) demonstrated by isoimmune rhesus monkey (Macaca mulatta) sera.

Twenty-one isoimmune sera produced in rhesus monkey (Macaca mulatta) containing type-specific antibodies for simian-type red cell antigens were tested for their cross-reactivity with red cells from crab-eating macaques (M. fascicularis). The majority of the antisera gave cross-reactions determining polymorphisms in the red cells of crab-eating macaques, homologous to those of rhesus monkeys. These results attest to the close taxonomic realationship between the two species of macaques, and have the practical implication that isoimmune sera produced for blood typing can also be used for typing red cells from related species, as has been also observed in studies on apes.     

Enzootic hepatitis A infection in cynomolgus monkeys (Macaca fascicularis)

During a toxicology study in cynomolgus (long-tailed or crab-eating) monkeys (Macaca fascicularis), a randomly distributed incidence of significantly increased hepatic enzyme activity was observed. Premedication hepatic enzyme activity in all monkeys of this study was normal, but increased alanine aminotransferase (ALT) activity was found in 4 of the 24 animals 2 weeks after initiation of the study and in 10 of 24 at 4 weeks. A drug-related effect was considered unlikely initially because the increases were not doserelated, and a 3-year review of 655 cynomolgus monkeys revealed a 15–20% incidence of increased hepatic enzyme activity. Good correlation was subsequently established between increased hepatic enzyme activity, active hepatitis A virus (HAV) infection, and histomorphologic confirmation of hepatitis (chronic periportal inflammation). Follow-up viral serodiagnostic screening of resident macaques revealed an overall incidence of anti-HAV IgG in 80% (155/193) of cynomolgus and in 70% (14/20) of rhesus monkeys. Serial screening demonstrated that several initially negative monkeys became seropositive for anti-HAV IgG, and a few acquired active infection (anti-HAV IgM). Among newly acquired cynomolgus monkeys, 2.5% (2/80) had an acute HAV infection, and 35% (28/80) eventually tested positive for anti-HAV IgG while quarantined in the primate facility. The characterization of an enzootic HAV infection in incoming monkeys posed a significant risk for the primate colony and handlers. Rigorous sanitation, isolation, and quarantine procedures, including personnel training and additional protective clothing for personnel working in the primate colony, reduced tho potential for transmission and arrested the outbreak. Experimenters should be cautious in ascribing toxicity to a test article based solely on increased hepatic enzyme activity associated with chronic periportal inflammation.     

Modeling depression in adult female cynomolgus monkeys (Macaca fascicularis)

Depressive disorders are prevalent, costly, and poorly understood. Male rodents in stress paradigms are most commonly used as animal models, despite the two-fold increased prevalence of depression in women and sex differences in response to stress. Although these models have provided valuable insights, new models are needed to move the field forward. Social stress-associated behavioral depression in adult female cynomolgus macaques closely resembles human depression in physiological, neurobiological, and behavioral characteristics, including reduced body mass, hypothalamic-pituitary-adrenal axis perturbations, autonomic dysfunction, increased cardiovascular disease risk, reduced hippocampal volume, altered serotonergic function, decreased activity levels, and increased mortality. In addition, behaviorally depressed monkeys also have low ovarian steroid concentrations, even though they continue to have menstrual cycles. Although this type of ovarian dysfunction has not been reported in depressed women and is difficult to identify, it may be the key to understanding the high prevalence of depression in women. Depressive behavior in female cynomolgus monkeys is naturally occurring and not induced by experimental manipulation. Different social environmental challenges, including isolation vs. subordination, may elicit the depression-like response in some animals and not others. Similarly, social subordination is stressful and depressive behavior is more common in socially subordinate monkeys. Yet, not all subordinates exhibit behavioral depression, suggesting individual differences in sensitivity to specific environmental stressors and enhanced risk of behavioral depression in some individuals. The behavior and neurobiology of subordinates is distinctly different than that of behaviorally depressed monkeys, which affords the opportunity to differentiate between stressed and depressed states. Thus, behaviorally depressed monkeys exhibit numerous physiological, neurobiological, and behavioral characteristics same as those of depressed human beings. The nonhuman primate model represents a new animal model of depression with great promise for furthering our understanding of this prevalent and debilitating disease and identifying novel therapeutic targets.