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.     

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.     

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.     

Comparison between the diameter of hair cross-sections and the thickness of the enclosed hairs in Japanese monkeys (Macaca fuscata fuscata)

The thickness of hairs from Japanese monkeys was measured by enclosing the hairs on slide glasses with balsam. Nine monkeys were used for the study. Forty to 69 hairs from the back were examined per head. High correlations between the thickness of the enclosed hairs and the diameter of cross-sections were obtained in all monkeys. In the Japanese monkey, therefore, it is considered possible to utilize enclosed hairs for measuring the thickness without preparing cross-sections. Moreover, the medullae of which the air layers are strongly related to thermoregulation, were readily observed in the enclosed hairs.     

A case of diverticular disease of the colon in a Japanese monkey (Macaca fuscata)

Diverticular disease of the colon was detected in a female Japanese monkey by X-ray examination. The monkey was 15 years old and had been kept under captive conditions for nine years. Lack of appetite and activity, and constipation were observed. The monkey was given fiber-rich vegetables and wild plants, and its appetite and activity then improved. Based on a consideration of various factors, it is suggested that one possible cause of the diverticulosis in this case was a low dietary fiber intake.     

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.     

Age-related changes in ovarian morphology from birth to menopause in the Japanese monkey,Macaca fuscata fuscata

Age-related changes in ovarian morphology were studied in female Japanese monkeys,Macaca fuscata fuscata. A total of 47 nonlactating females of various ages ranging from new-born to >28 yr old were used. Ovarian size increased during the first decade of life, reached a plateau at around 10 yr. This was followed by a gradual decline throughout the remaining life span. The ovarian cortex of new-born animals consisted of numerous clusters of mitotic primordial germ cells. Such mitotic germ cells were observed even in the ovary of 28-day-old animal, but were not found in any animal after 1.5 yr of age. Numbers of primordial follicles decreased exponentially with the advance of age, and only a few primordial follicles were observed after about 16 yr of age. The numbers of primary and tertiary follicles increased from ages 4 to 16 yr, with a peak at 8 to 10 yr, and then decreased gradually. Developing tertiary follicles were observed as early as 1.5 yr of age. About 40% of tertiary follicles were atretic follicles throughout life, and their size was similar to that of developing tertiary follicles. Corpora lutea or corpora albicantia were found in ovaries more than 4 yr old. Remnants of corpora lutea and corpora albicantia, together with thick-walled blood vessels and fibrosis, became apparent in ovaries after 16 yr, and were observed characteristically in ovaries over 26 yr of age. There was no significant difference in the number or in the size of tertiary follicles between the breeding and nonbreeding seasons.     

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.     

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.     

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.     

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.     

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.     

A cytogenetic study on congenital limb malformations in the Japanese monkey (Macaca fuscata)

A cytogenetic investigation was performed on 88 Japanese monkeys (Macaca fuscata) with abnormal limbs from 11 free-ranging provisioned troops including nine individuals with abnormalities indistinguishable as to whether they were congenital or injurious. All of the monkeys with abnormal limbs including the nine questionable individuals had the same karyotypes as those of normal individuals. The chromosome number was 42, consisting of 20 bi-arm autosome pairs and a submetacentric X-chromosome and Y-chromosome. The ninth chromosome pair, which was the only chromosome pair with remarkable secondary constriction, displayed length polymorphism of the centromeric C-band and secondary constriction in both deformed and normal monkeys. These kinds of variants have also been commonly found in other monkey species, which have almost the same karyotype as the Japanese monkey and have not been reported to show frequent occurrence of limb malformation. We concluded therefore that chromosomal abnormalities could be excluded from the main causal factors for limb malformations of 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.     

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.     

Hematological analyses of the Japanese monkey (Macaca fuscata)

Various hematological examinations were performed on a total of 208 Japanese monkeys (Macaca fuscata). One hundred and fifty-eight of the monkeys were originally from different habitats in the western part of Japan, where they existed as free-ranging animals. The remaining 50 monkeys were kept in an open-enclosure for about one year. Laboratory examinations on blood specimens included the following; the erythrocyte and leukocyte counts, hemoglobin concentration, hematocrit, the specific gravity of the blood and plasma, protein concentration of the plasma, SGO-T, SGP-T, A/G ratio and the erythrocyte sedimentation rate. Results were similar to those reported for otherMacaca species. When the data reported here was compared with the known values for man, the Japanese monkey showed lower values for the erythrocyte count, hemoglobin concentration, hematocrit, and the specific gravity of the blood. Higher values were shown for the leukocyte count and SGO-T activity, with a wider overall range of variation.     

Clinical examinations of the Japanese monkey (Macaca fuscata)

Since 1962 clinical examinations have been performed on all 466 Japanese monkeys from the troops of the western part of Japan.During the external inspection we found a few cases of malformation of the hand and foot in some troops, but except for these they were in good physical condition, negative in tuberculin test and in Shigella and Salmonella infection.In all troops a high rate of helminthic infection was detected and there was a difference in the rate of occurrence of certain helminths betweenMacaca fuscata fuscata andM. fuscata yakui. No single case with the antibody to the B Virus was encountered, and it seems that no infection of the B Virus is present among the Japanese monkey.The free-ranging condition under which the Japanese monkey inhabits in troops seems to be satisfactory and they seem to have no serious problem of any kind at present.     

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.     

Effects of an intrauterine copper device on serum copper, endometrial histology, and ovarian, hepatic, and renal functions in the Japanese monkey (Macaca fuscata fuscata).

A copper intrauterine device (Cu-IUD) was inserted transabdominally into the uterine cavity of eight Japanese monkeys (Macaca fuscata fuscata) for 4 to 6 months, and effects on various organ functions were examined. Results showed no significant effects on the menstrual cycle length, serum levels of LH, estradiol-17 beta, progesterone or clinical biochemical data such as serum copper, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, lactic dehydrogenase, and blood urea nitrogen. Histology revealed edema and infiltration of eosinophilic leukocytes in the endometrium treated with a Cu-IUD.