Parturition in a free-ranging Japanese monkey (Macaca fuscata)

Parturition behavior of a multiparous female and her interactions with group members throughout the birth process were recorded for a free-ranging Japanese monkey (Macaca fuscata). The female showed evidence of 18 contractions during the 35 min prior to delivery, with a mean duration and a mean intercontraction interval of 30 sec and 96 sec, respectively. These values were similar to those in individually caged Japanese monkeys. Some adult females remained in proximity to the female who was giving birth during the prepartum phase, and her 2-year-old daughter watched the delivery of the infant. Even during the prepartum phase the female moved in order to keep up with the group which traveled from the feeding site to a sleeping site in the forest.     

A preliminary study on hair length in the Japanese monkey (Macaca fuscata fuscata)

The hair length of Japanese monkeys was investigated. The hair of the Japanese monkey is long on the back and the lateral side of the upper arm and short on the back of the hand. There was variation in the length of hairs in the same region of the body. The distribution of hair length approximated to a normal curve and did not display any marked bias or skewness. The increase in length of hairs was remarkable from 0 to 1 year of age, and then continued at a constant rate. Sex differences in hair length were not so remarkable at any age.     

Annual changes in hair length of the Japanese monkey (Macaca fuscata fuscata)

The hair length of Japanese monkeys was investigated for a period of one year and the molting phenomenon was clarified. Nine monkeys were employed in the study. The molting of the Japanese monkey was found to be of a seasonal type and occurred once during the year. The molting continued for one to four months in each monkey. The hair of the Japanese monkeys was wholly replaced during the period from April to August. The hair length was thus short in summer, and long in winter. Hair replacement in pregnant females began after parturition and was generally later than that in other individuals. During molting, both new and old hairs could be observed simultaneously in the same region of the body. The hair replacement ended around summer when the hair became the shortest. The new hairs continued to grow after molting and became the longest towards autumn or winter. Thus, the summer coat and the winter coat were essentially the same in the Japanese monkey. Such annual changes in the hair of the Japanese monkey were considered to be suitable for the climate of Japan.     

Characteristics of serial cross-sections of hairs of the Japanese monkey (Macaca fuscata fuscata)

The characteristics of serial cross-sections of hairs collected from an adult male Japanese monkey were investigated. Cross-sections were made of five to eight pieces per hair. The shapes of the cross-sections were elliptical or rounded on the whole. The fibre indices of the sections ranged from 83 to 100. In particular, those of proximal (basal) sections were close to 100. The hair diameter was 86.4 μ at maximum and 27.2 μ at minimum. A tendency was observed for the longer hairs to have thicker diameters. The changes in thickness along the fibre shaft were slightly different in relation to hair length. The thickest point was at around the middle of the fibre in the intermediate hair, somewhat towards the top of the central part in the long hair, and somewhat towards the base in the short hair. The hair of the Japanese monkey, however, was considered to be scanty in changes along the fibre shaft in comparison with many other animals. Medullae could scarcely be seen in the short hair and in the terminal and proximal sections of all hairs. Their shapes in cross-section were not uniform and rough at the margins. The fibre-medulla indices were generally less than 30 and smaller than those of many other mammals. Pigmentary granules were observed in all sections examined. The granules were black-grey in sections of the black-grey coloured part and yellow in the yellowish sections. They were dense in distal sections and scarce in sections close to the base. The cross-sectional appearance of the thickest part of the long hair was considered to be useful for hair identification, since it was good in pigmentation and medullation and relatively small fibre index.     

Successful artificial insemination for indoor breeding in the Japanese monkey (Macaca fuscata) and the cynomolgus monkey (Macaca fascicularis)

Methods of artificial insemination (AI) for indoor breeding in the Japanese monkey and the Cynomolgus monkey were investigated. For the Japanese monkey AI was carried out in six females during the winter mating season and in six females during the summer non-mating season. During the mating season, semen was inseminated near ovulation time in natural menstrual cycles. In the mating season study, three females inseminated at the uterine cavity became pregnant. Three inseminated at the cervical canal failed to become pregnant. For the non-mating season study, ovulation was induced artificially by PMSG and hCG and AI was carried out near the induced ovulation time. In the non-mating season, no animals became pregnant. Of four Cynomolgus monkeys used, pregnancy occurred in two animals inseminated near ovulation time in natural menstrual cycles. AI occurred at the uterine cavity in one and cervical canal in the other. In both species ovulation was verified by laparoscopy. Semen was collected by penile electro-stimulation then diluted to 2.5 to 5.0×10⁷/ml with Whitten's medium. Diluted semen of 0.2l was inseminated at the uterine cavity or cervical canal. Our results indicate the usefulness of vaginal AI as a method of artificial indoor breeding.     

Copulatory behavior unaccompanied by ovulation in the Japanese monkey (Macaca fuscata)

Copulatory behavior unrelated to conception is sometimes observed in some non-human primates including the Japanese monkey. In the present study, the authors examined whether a mature follicle or a newly formed fresh corpus luteum was observed in the ovaries of female Japanese monkeys which displayed the copulatory behavior unrelated to conception. Post-conception copulatory behaviors were observed in three out of four females usually kept in individual cages in an air-conditioned room, and in two out of three females without infants kept in an outdoor group cage. However, neither a mature Graafian follicle nor a fresh corpus luteum formed newly after conception was observed in any of these females by laparoscopic examinations conducted immediately after termination of the copulatory behavior. In females with infants born in the preceding birth season, copulatory behaviors were observed in three out of four females kept in the outdoor group cage, and in two out of four females in a free-ranging troop. Ovulation was confirmed in one case out of the three kept in the outdoor group cage, but neither a mature follicle nor a newly formed corpus luteum was observed in the remaining four females. These findings suggest that copulatory behavior in the Japanese monkey is not always controlled by the development of a follicle or ovulation in the ovary.     

Use of a mirror to direct their responses in Japanese monkeys (Macaca fuscata fuscata)

Two male Japanese monkeys used a mirror to inspect an object attached to their bodies but not directly visible. These monkeys had been trained previously to use a mirror to guide their hand to a target. In Experiment 1 their behavior in the presence of a mirror was observed. In Experiment 2 the monkeys used the mirror to locate a picture projected on a screen to the left or right rear side of the cage. In Experiment 3 the monkeys used a mirror to observe and finally grasp an object attached behind their heads. Two monkeys who were not trained to use a mirror to obtain an otherwise hidden object did not show such behavior.     

Mirror guided behavior in Japanese monkeys (Macaca fuscata fuscata)

Two male Japanese monkeys were trained to use a mirror to reach an object that could not be seen directly. Training to use a mirror in this way proceeded, step-by-step, from reaching a piece of apple to key-tracking. In Experiment 1 the monkeys were trained to use the mirror to locate a desired object, a piece of apple in a box facing the mirror, which could be seen only by looking into the mirror. The apple, once located, however, could be grasped without further reference to the mirror. This behavior is referred to as mirror mediated object discrimination. In subsequent experiments the monkeys could not reach the goal object except by observing it and his hand movement in the mirror. In Experiment 2 the target was a piece of apple visible in the mirror, in Experiment 3 an illuminated key and in Experiment 4 a series of keys which were illuminated sequentially. Mirror guided behavior such as shown in Experiment 2, 3, and 4 has not previously been demonstrated in monkeys.     

Differences in hair density of Japanese monkeys (Macaca fuscata fuscata) with locality and age

The hair density of free-ranging Japanese monkeys (Macaca fuscata fuscata) living in three different areas was investigated. The Japanese monkeys had thicker hair than other macaques. The hair density in the Japanese monkeys varied with locality: the northern monkeys had thicker hair than the southern ones. The density did not vary markedly with age up to 3 years of age, but then decreased gradually up to adult age (≧7 years old). The remarkable growth of the trunk suggested that the total number of hairs increased with age, especially during the period as a juvenile.     

Object manipulation in a captive troop of Japanese monkeys (Macaca fuscata): A developmental analysis

A captive troop of Japanese monkeys (Macaca fuscata) was presented with a nylon rope, a wooden cube, and an iron tube, and their subsequent manipulations were observed in detail. In total, 202 manipulation patterns were distinguished on the basis of three components: the actions performed, body-parts used, and relations to other objects. The developmental changes in these modes of manipulation were analyzed cross-sectionally, revealing four characteristics: (1) the most manipulative members of the troop were those aged 2–3 and 4–6 years old; (2) most of the manipulatory repertoire appeared by 4–6 years old; (3) actions such as Roll, Rub, and Slide and the use of bodyparts continued to increase in variety until 4–6 years old, while the variety of other actions showed plateaus after 2–3 years old or an earlier age; and (4) secondary manipulations appeared at 1 year old and continued to increase in variety even after 4–6 years old.     

Digging and eating of underground plant-parts by wild Japanese monkeys (Macaca fuscata)

It has been reported that Japanese monkeys pull out and eat underground parts of plants, but they do so only a little and occasionally. The authors observed that wild Japanese monkeys in the mountains area near Hinohara Village ate underground plant-parts as one of the main components of their diet and they spent a lot of time digging for them. From information obtained from local old people, it appears that they have exhibited this behavior for many years as part of their feeding repertoire.     

Borna disease virus RNA detected in Japanese macaques (Macaca fuscata)

We have examined the seroprevalence of BDV in wild Japanese macaques (Macaca fuscata) in the peninsula (Chiba prefecture), Japan. Serum samples from macaques were examined by the ELISA, Western blot and immunofluorescence assays to detect the presence of serum antibodies that react specifically to BDV antigens. Among 49 investigated individuals, 6 (12.2%) showed positive reaction to BDV antigens. RT-PCR studies detected BDV sequences in brain tissue of one case among four seropositive cases examined. Sequence analysis revealed a high degree of genetic conservation between BDV sequences derived from Japanese macaques and those documented for other animal species. Nevertheless, phylogenetic analysis revealed unique differences between macaque and other species derived BDV sequences.     

Recognition of facial expressions in a Japanese monkey (Macaca fuscata) and humans (Homo sapiens)

Recognition of facial expressions by a Japanese monkey and two humans was studied. The monkey subject matched 20 photographs of monkey facial expressions and 20 photographs of human facial expressions. Humans sorted the same pictures. Matching accuracy by the monkey was about 80% correct for both human and monkey facial expressions. The confusion matrices of those facial expressions were analyzed by a multi-dimensional scaling procedure (MDSCAL). The resulting MDS plots suggested that the important cues in recognizing facial expressions of monkeys were “thrusting the mouth” and ‘raising the eyebrows.” Comparison of the MDS plots by the monkey subject with those by human subjects suggested that the monkey categorized the human “happiness” faces. This may suggest that the monkey has an ability to recognize human smile face even though it is learned. However, the monkey did not differentiate the human “anger/disgust” faces from the human “sad” faces, while human subjects clearly did. This may correlate with the lack of eyebrow movement in monkeys.     

Measurement of serum IgE antibodies against Japanese cedar pollen (Cryptomeria japonica) in Japanese monkeys (Macaca fuscata) with pollinosis.

IgE antibodies against allergens of Japanese cedar (Cryptomeria japonica, CJ) pollen in the serum of seven Japanese monkeys (Macaca fuscata) with pollinosis were measured by fluorometric indirect enzyme-linked immunosorbent assay (ELISA). All of the monkeys were found to have specific IgE to the crude pollen antigen. The specific IgE levels were well correlated with those determined by the Pharmacia CAP system. IgE antibodies were then assayed with two kinds of purified allergens (Cry j I and Cry j II) by the ELISA. We found that five monkeys had specific IgE to both allergens, although the other two had IgE only to Cry j I or Cry j II; there is different immune responsiveness to the two major allergens in the monkeys.     

Birth of the Japanese Monkey (Macaca fuscata) infant following in-vitro fertilization and embryo transfer

The first successful birth by in-vitro fertilization (IVF) and embryo transfer (ET) in the Japanese monkey was described. IVF was carried out by using oocytes collected after ovarian stimulation and sperms collected by rectal electro-ejaculation. The embryos were incubated for 36–66 hours and then transferred to the fallopian tube of the recipient via the fimbria under laparoscopic observations. Four recipients received their own embryos and six recipients received donor embryos. Two recipients of six that received donor embryos became pregnant after receiving one 3-cell and one 2-cell embryos, and one 4-cell and one 2-cell embryos, respectively. On healthy terminated male infant was delivered 166 days after ET, but the other aborted on day 128. This successful birth indicates the usefulness of our IVF/ET method for systematic indoor artificial breeding and preservation of endangered primates species.     

Immobilization with a single dose of ketamine hydrochloride and a combination of xylazine hydrochloride-ketamine hydrochloride and antagonism by yohimbine hydrochloride in the Japanese monkey (Macaca fuscata)

Forty-nine free-ranging Japanese monkeys (Macaca fuscata) were immobilized with 4.3–15.6 mg/kg (mean±S.D.=10.0±2.5 mg/kg) of ketamine hydrochloride (HCl), and 27 Japanese monkeys kept in enclosures were immobilized with a combination of 0.8–1.4 mg/kg (1.0±0.2 mg/kg) of xylazine HCl and 4.0–7.1 mg/kg (5.0±0.6 mg/kg) of ketamine HCl. In the xylazine HCl-ketamine HCl combination, good myorelaxation was induced. The mean induction times for the single dosage of ketamine HCl and the xylazine HCl-ketamine HCl combination were 2.8±1.5 min and 6.9±4.4 min, respectively. The mean immobilization times with the single dosage of ketamine HCl and the xylazine HCl-ketamine HCl combination were 39.3±16.5 min and 58.8±34.2 min, respectively. A half dose of ketamine HCl in combination with xylazine HCl could also immobilize Japanese monkeys successfully. Administrations of 0.5 mg/kg i.v. and 1.0 mg/kg i.m. of yohimbine HCl as an antagonist to xylazine HCl at 30 min after the induction reduced the immobilization time to 31.4±0.5 min and 49.0±22.1 min, respectively. Yohimbine HCl appears to be an effective antagonist to combination anesthesia by xylazine HCl-ketamine HCl in the Japanese monkey.     

Lactation in the Japanese monkey (Macaca fuscata): Yield and composition of milk and nipple preference of young

Changes in the yield and chemical composition of milk, together with those in the nipple preferences and suckling behavior of infants, were followed in three lactating Japanese monkeys rearing single infants under laboratory conditions at monthly intervals for six months after their paturition. Milk accumulating in the mammary glands during a 4-hr separation of the infant was collected by milking under anesthesia with the aid of a physiological dose of oxytocin. The stage of full lactation appeared to last for about two or three months after parturition. The milk at this stage contained 14.0% of total solids, 4.2% of lipids, 1.6% of proteins, and 6.2% of lactose, and the concentrations of Na, Cl, and K in the milk water were 7.4, 15.1, and 5.9 mM, respectively. From the 9th or 13th week of lactation onwards, according to the individual, the milk composition changed appreciably and the time during which the young left hold of the mother's nipple also increased. The weaning of young in the Japanese monkey appears to begin during the 3rd or 4th month of age. The milk production then wanes and almost ceases by the end of the 6th month. The nipple preference of the young was generally established completely by the 3rd, or the 8th at latest, week of age. However, no difference in either the yield or composition of the milk secreted was found between the mammary glands of the preferred and non-preferred sides. Without regard to the apparent nipple preference, infants seem to ingest milk from the mother's breasts of both sides. Accurate estimation of the rate of milk production could not be achieved, but the rate was expected to be 150–200 g/day at the height of lactation based on the relation between the mother's body weight and the milk production rates of other primate species. A disparity was noted between the observed and estimated values for the milk yield, and a diurnal fluctuation in the milk secretion of the Japanese monkey was inferred. This study was conducted through the official system of the Primate Research Institute, Kyoto University, for cooperative research work with other institutions.     

Hepatic neuroendocrine carcinoma in a Japanese macaque (Macaca fuscata)

Primary neuroendocrine neoplasm of the liver is extremely rare in both humans and non‐human primates. The present report describes the clinical and pathological findings of an aged Japanese macaque (Macaca fuscata) with hepatic neuroendocrine carcinoma. To our knowledge, this is the first report of hepatic neuroendocrine neoplasm in macaques.     

Monitoring the reproductive status of Japanese monkeys (Macaca fuscata) by measurement of the steroid hormones in fecal samples

The menstrual cycles as well as the pregnancy in female Japanese monkeys (Macaca fuscata) were monitored by measuring the fecal estradiol concentrations and relative amounts of fecal progesterone. Steroids from fecal samples were extracted by using a previously developed simplified two-step method and then measured by radioimmunoassay. We successfully demonstrated that the two-step method is effective and convenient for monitoring the reproductive status of Japanese monkeys.