Reproduction in the slender loris (Loris tardigradus malabaricus)

A breeding colony of slender lorises (Loris tardigradus malabaricus) was studied to obtain data for comparison with other prosimian species, to contribute reproductive information for improving management of captive lorises, and to resolve some uncertainties in the literature regarding reproduction in the slender loris. At the Duke University Primate Center, a female slender loris reached sexual maturity at approximately ten months of age and conceived at one year of age. The length of the estrous cycle was 29–40 days, with copulation occurring over two consecutive days during estrus. Gestation length was 166–169 days. Litter size for each six births was one. Conception did not occur during an immediate post-partum estrus, but four months after birth, resulting in a 9 1/2-month interbirth interval. There was no evidence of reproductive seasonality. Lactation lasted between five and seven months. Reproductive rates of slender lorises are among the lowest of primates less than 500 g. Differences in reproductive parameters may exist between different subspecies of slender lorises.     

The subependyma of the primate, slow loris (Nycticebus coucang coucang)

The subependymal plate of the primate slow loris (Nycticebus coucang coucang) has been studied by electron microscopy. It is composed of a mixed population of several cell types in which the subependymal cells preponderate. Free subependymal cells are found in the ‘border area’ near the corpus callosum or the neuropile of the caudate nucleus. In common with the subependymal cells they show a scanty cytoplasm containing mostly free ribosomes. Typical neuroglial cells namely, microglia, astrocytes and oligodendrocytes are also identified in this region. Among the various cell types mentioned there are present also a few occasional cells which have features bearing a resemblance to the subependymal cell on the one hand and to the microglia on the other. The morphological evidence suggests that in parallel with the macroglia the microglia could be derived by stepwise transformation of the subependymal cells.     

Reproduction,physical growth and behavioral development in slow loris (Nycticebus coucang,Lorisidae)

Reproduction of slow loris maintained in in- and outdoor enclosures in the natural day-night-cycle of southern Germany seems to be seasonally dependant. Mating occurs during summer, delivery of offspring during winter. Gestation length as determined from mid-estrus was 186–187 days. Copulation takes place over two to five consecutive days during estrus. Litter size for each of the recorded births was one. Lactation lasts for five to seven months. Sexual maturity is reached at about 1 1/2 to 2 years. Physical growth and the first appearance of main locomotor, behavioral and vocal patterns are described until nutritive weaning. With regard to acoustic structures, the vocal repertoire of newborn slow loris is quite similar to that of adults. During ontogeny main changes are discerned in the temporal pattern and pitch frequency of vocalizations and in their use. Results are compared with other primates.     

Neuroglia in the corpus callosum of the primate, slow loris (Nycticebus coucang coucang)

The corpus callosum of adult slow loris consists of a mixed population of several cell types, i.e. free subependymal cells, oligodendrocytes, astrocytes and microglia. The free subependymal cell is rather small and slender with a somewhat patchy nucleus. It shows scanty cytoplasm with free ribosomes. Oligodendrocytes vary both in nuclear and cytoplasmic densities and can be divided into three classes: light, medium dense and dark types. Their cytoplasm contains microtubules, rough endoplasmic reticulum and Golgi saccules. Astrocytes are pale cells with large amount of filaments in their cytoplasm. Microglia are small cells with granulated nuclei. The cells often show large cytoplasmic protrusions containing the usual cell organelles and lipofuscin bodies in their cytoplasm. Lastly, cells with typical features of neurons are occasionally encountered among the white matter.     

Excretion of radiolabeled estradiol metabolites in the slow loris (Nycticebus coucang)

The excretion pattern of estradiol was studied in the slow loris Nycticebus coucang) and the ring-tailed lemur (Lemur catta) in order to compare steroid excretion in two representative prosimian species. Daily urinary estrone conjugate measurements in the female loris provided little information when applied over prolonged periods. As a result of these negative data, a metabolic study was performed to determine if estrogen excretion patterns in the slow loris differed from those in the lemur, where urinary assays proved a useful tool in characterizing reproductive cycles. Radio-labeled estradiol was injected intravenously, and serial urine and fecal collections were analyzed for radiolabeled metabolites. The results of these studies demonstrate that more than 92% of the radiolabel was excreted in the feces of the loris, in contrast to only 16% excreted in the feces of the lemur.     

Activity changes with illumination in slow loris Nycticebus coucang

The relationship between illumination and levels of activity of three adolescent slow lorises (N. coucang) was studied in a habitat — simulated, captive environment. The frequency of low, medium and high activity behaviors were recorded under four intensities of illumination (0.061, 0.120, 0.380 and 4.000 footcandles (ft-c)). The data suggest that N. coucang's nocturnal activity level is an inverse function of illumination, with low activity behaviors occurring during moonlight-like intensities and high activity behaviors during twilight-like intensities. The relationship was nonlinear, indicating a threshold mechanism (between 0.120 and 0.380 ft-c) analogous to a crepuscular niche in the wild.     

Functional anatomy of the trunk musculature in the slow loris (Nycticebus coucang)

Lorisid locomotor and postural behaviour exhibits a number of features that distinguish it clearly from other primates. The comparative myological study of the trunk in the slow loris (Nycticebus coucang) and the squirrel monkey (Saimiri sp.) presented here reveals differences that are related to unique aspects of lorisid positional behaviour. While quadrupedal running and leaping requires flexion and extension of the spine, slow climbing quadrupedalism in lorisids depends on spinal lateral flexion and rotation. The contrasting development of the epaxial musculature in the two species dissected reflects these different requirements. Bipedal suspension is a common posture in the lorisids during which rotation and dorsiflexion of the head is made possible by the robustly developed deep, dorsal, cervical musculature. The long lower lever arm in the M. rectus abdominis may play a significant role in the ventroflexion required to regain a quadrupedal stance. © 1995 Wiley-Liss, Inc.     

The chromosome complement of the slow loris (Nycticebus coucang Boddaert, 1785)

The chromosome complements of two male and two female adult slow lorises (Nycticebus coucang) have been studied in blood cultures cultivatedin vitro for three days. We have observed basic differences in arrangement from previous results, and the existence in the complement of a dimorphic pair not described before in this species. This dimorphic pair does not fit with any known type of chromosome dimorphism or polymorphism, either in rodents or primates. The diploid chromosome number is 50. Nine of the chromosome pairs are metacentric, the remaining 15 pairs, submetacentric. The X chromosome is a long submetacentric, ranking 4 in order of decreasing size. The Y chromosome is a rather long metacentric and ranks 15 in the same order. The autosomes, 2 to 10µ long in metaphase with arm ratios ranging from 1.14 to 2.65, are paired and arranged in order of decreasing size. Chromosome pair No. 5 is dimorphic, one of the chromosomes in the pair being constantly longer than the other. An idiogram of the haploid chromosome complement is presented, incorporating measurements of 30 analyzed nuclei.     

Eastern limit of distribution of the slow loris,Nycticebus coucang

The easternmost known record of the slow loris,Nycticebus coucang, is Tawitawi, Philippines. A report of this species in Mindanao, 500 km northeast of Tawitawi, is based on a mislabeled specimen.     

Reproduction in the crowned lemur (Lemur coronatus) in captivity

Four pairs of captive crowned lemurs (Lemur coronatus) were studied during their annual breeding season in order to obtain baseline data on their reproductive biology for comparison with other Lemur species and to enhance their captive breeding success. Vaginal smears, testicular measurements, and records of the Duke University Primate Center provided the presented data. During a single breeding season, females cycled an average of three times, with an average cycle length of 34 days. Cycles were detected between November and March. Vaginal estrus and copulations were limited to one day per cycle. After 125 days of gestation females gave birth to one or two young. Both sexes attained sexual maturity at an age of about 20 months. Mean male testis size peaked in late December; at the same time, three of the females experienced their first estrus. Based on all available data, there was a significant positive correlation between cycle length and gestation length in the genus Lemur.     

The functional anatomy of the ankle and foot of the slow loris (Nycticebus coucang)

The slow loris must use its limb for stabilization and forward progression during arboreal climbing. The orientation of the limb joints, hip, knee, talo-crural, sub-talar and tarso-metatarsal, correlate with movement upon supports lying below and in line with the body axis. The musculature controlling the joints of ankle and foot, and the integument of the sole further indicate the integration of this adaptation.     

Temperature regulation in a hypometabolic primate, the slow loris (Nycticebus coucang).

Six slow loris were exposed to air temperatures between 10 degrees C and 40 degrees C. Rectal temperature was stable (mean, 34.8 degrees C) at air temperatures between 17 degrees C and 31 degrees C; at higher air temperatures, the animals became hyperthermic. Oxygen consumption was minimal at air temperatures of 31.4-36.6 degrees C; the mean value (0.250 ml O2 g-1 h-1) was only 36% of the expected level for a eutherian Mammal. The slow loris increased its heat production at lower air temperatures. Thermal polypnea occurred in response to heat, and some of the animals were able to dissipate their entire metabolic heat production at lower air temperatures. Thermal polypnea occurred in response to heat, and some of the animals were able the combined thermal conductance of the tissues and haircoat was 73% of the predicted values. It was concluded that, in spite of its low metabolic rate, the slow loris had effective responses to moderate cold, and that, in addition, it was well adapted to a hot climate.     

Mother-infant interactions in captive slow lorises (Nycticebus coucang)

Information is presented about mother-infant interactions and infant development in a rarely studied prosimian primate, the slow loris (Nycticebus coucang). Four dyads were observed, by means of closed circuit TV, in a semi-natural environment for 1 hour per day three times a week. Infants were inactive for the first 6–8 weeks. Although mothers carried infants, they also left them alone for substantial periods of time after the 1st week. Over the 20-week study period, there was a significant decline in ventral contact but not in sitting within 12 inches or engaging in active social interactions. By the end of the study, infants were not yet fully independent. Three of the 4 were primarily responsible for maintaining physical closeness to the mother; they made most of the approaches and mothers made most of the departures. However, only 2 of the 4 infants had assumed responsibility for the initiation and maintenance of social interactions with the mother. By comparison with other nocturnal prosimians of similar size, the rate of development is relatively slow. Unlike many anthropoids, mothers were not strongly protective or rejecting. They did not bring infants back to a fixed location or try to prevent infants from leaving them; and the decline in ventral contact was not accompanied by fights between the pair. The 3 group-living mothers were more protective than the single individually housed mother, and it would seem advisable to isolate mother-infant pairs in laboratory breeding colonies.