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At least 19 recordsLinked to original sources
PubMed1986

Ontogeny and cranial morphology of the tympanic region of the Tupaiidae, with special reference to Ptilocercus.

The structure of the tympanic region of the skull of Ptilocercus lowii was studied in an embryo of 30 mm crown-rump length and in 5 osteocrania. As in Tupaia, the anterior wall of the bulla of Ptilocercus is not completed by a tympanic process of the alisphenoid, contrary to earlier reports. Ptilocercus resembles Tupaia in the following derived characters. The ventral wall of the tympanic cavity is formed by a rostral entotympanic and by a caudal tympanic process of the petrosal. The entotympanic develops in primary connection with the tubal cartilage. The tympanic aperture of the auditory tube is bordered by the entotympanic. The ring-shaped tympanicum is covered by the entotympanicum and is aphaneric. The musculus tensor tympani is lacking. Among mammals, these characters can be regarded as synapomorphic for the Tupaiidae, that is, to have been present in the common ancestor of the two subfamilies. From the evidence of the tympanic region, the Tupaiidae, therefore, form a monophyletic group. Besides these synapomorphies, there are remarkable differences between Ptilocercus and Tupaia in the structure of the bulla. In Ptilocercus the bulla is smaller and less pneumatized than in Tupaia. An anterior intrabullar septum, present in Tupaia, is lacking in Ptilocercus. The epitympanic wing of the alisphenoid is smaller in Ptilocercus than in Tupaia. A lateral prefacial commissure of the tegmen tympani is present in Ptilocercus, but absent in Tupaia. The caudal tympanic process of the petrosal is larger in Ptilocercus than in Tupaia. These characters are autapomorphic for the Ptilocercinae and for the Tupaiinae, respectively. They demonstrate that the auditory bulla of Ptilocercus and that of Tupaia have evolved independently to a considerable extent. An early phylogenetic separation of their respective ancestors seems likely. The tympanic region of the skull provides no evidence for close relationships of the tree shrews to the primates or to any other eutherians. The classification of the Tupaiidae in a separate order, Scandentia, is supported.

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PubMed1991

Retinal [125I]iodomelatonin binding sites in the tree shrew (Tupaiidae).

The characteristics of melatonin-binding sites labelled by [125I]iodomelatonin in membrane preparations from the tree shrew retina were determined. Specific binding of [125I]iodomelatonin to the membrane preparations of tree shrew retina was rapid, stable, saturable, and reversible. Among the indoles tested only 6-chloromelatonin, melatonin and N-acetylserotonin had significant affinities to the [125I]iodomelatonin binding site. Scatchard analysis of the membrane preparations revealed a dissociation constant (Kd) of 51.0 +/- 16 pM and a total number of binding sites (Bmax) of 1.97 +/- 0.6 fmol/mg protein.

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PubMed1998

The morphogenesis of the arteries of the pelvic extremity. A comparative study of mammals with special reference to the tree shrew Tupaia belangeri (Tupaiidae, Scandentia, Mammalia).

The ontogeny of the arteries of the pelvic extremity of Tupaia belangeri was investigated by light microscopy on the basis of serial sections of 30 embryos, dating from day 17 to day 42 post-copulation. In Tupaia, the gestational period takes approximately 43 days. Additionally, a 3-D reconstruction of the pelvic region and the right leg of a 22-day embryo was prepared. The arteries of an adult Tupaia were studied on the basis of a corrosion cast. The results were compared with the ontogeny of the arterial system of other mammals. In the 17-day embryo, the anlage of the pelvic extremity is penetrated by a capillary plexus. In the 18-day embryo, the a. ischiadica reaches the pelvic limb bud, representing the primary axial artery. On day 19, its r. perforans tarsi extends from the plantar to the dorsal aspect of the foot plate. The a. ischiadica is the main artery of the leg until the stage of the 22-day embryo. Afterwards, the peripheral arteries supplied by it are taken over by the a. iliaca externa and its extension, the a. femoralis. The a. iliaca externa springs from the a. iliaca communis in the 19-day embryo. From day 21 to day 22, the capillary plexus, which is nourished by the a. femoralis, closely approaches the a. ischiadica, and finally, a connecting branch joins the a. ischiadica. The a. ischiadica is then reduced to the a. glutea caudalis, and the aa. femoralis, poplitea profunda (at the cranial aspect of the m. popliteus), and interossea become the main arteries of the pelvic extremity. The a. poplitea superficialis, lying at the caudal aspect of the m. popliteus, and its continuation in the crural region, the a. peronea, develop until the 25-day embryo. The a. peronea gives rise to an r. perforans which penetrates the membrana interossea towards the dorsum of the foot. As a result of a shift of the origin of the a. iliaca externa in the proximal direction, the length of the a. iliaca communis gradually decreases until, on day 24, the a. iliaca externa springs directly from the lateral wall of the aorta. In the 20-day embryo, the a. iliaca externa gives rise to an a. circumflexa ilium profunda towards the lateral pelvic wall, and in 23-day embryos, to the a. profunda femoris. The main branches of the a. profunda femoris develop until day 24. At the same time, the aa. circumflexa femoris lateralis and nutricia ossis femoris arise from the a. femoralis. The a. saphena, which is already recognizable in the 23-day embryo, gives rise to the a. genus descendens, and as an a. plantaris medialis, to four aa. digitales plantares communes (I-IV) at the planta pedis. The development of the a. tibialis cranialis on day 25 takes place independently and without any topographic relation to the a. saphena, which functionally replaces the a. tibialis cranialis in some other mammals. In the 26-day embryo, the aa. peronea and tibialis cranialis extend to the dorsum of the foot where they continue as the aa. dorsales pedis profunda and superficialis. The fourth main artery of the lower leg, the a. caudalis femoris, which is first observed in the 20-day embryo, reaches the lateral aspect of the foot on day 24. Its r. calcaneus runs to the planta pedis. In 30-day embryos, the aa. digitales plantares propriae have differentiated. The corresponding dorsal arteries and the superficial plantar vascular are develop until day 35, so that all important arteries of the pelvic extremity, which are seen in the corrosion cast of the adult, are recognizable. Among the embryos and the adult Tupaia studied, individual variation is minimal. The developmental stage at which the arteries of the leg acquired a secondary vascular wall was ascertained. Only a vessel with a primary vascular wall can dissolve into a capillary plexus later on (e.g., a. interossea). In contrast, the course of an artery which has acquired a secondary vascular wall is determined, because modifications of the course of a vessel often need a capillary plexus as an intermediate st

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PubMed2006

Postnatal allometry of the skeleton in Tupaia glis (Scandentia: Tupaiidae) and Galea musteloides (Rodentia: Caviidae)--a test of the three-segment limb hypothesis.

During the evolution of therian mammals, the two-segmented, sprawled tetrapod limbs were transformed into three-segmented limbs in parasagittal zig-zag configuration (three-segment limb hypothesis). As a consequence, the functional correspondence of limb segments has changed (now: scapula to thigh, upper arm to shank, fore arm plus hand to foot). Therefore, the scapula was taken into account in the current study of the postnatal growth of the postcranial skeleton in two small mammalian species (Tupaia glis, Galea musteloides). Comparisons were made between the functionally equivalent elements and not in the traditional way between serially homologous segments. This study presents a test of the three-segment limb hypothesis which predicts a greater ontogenetic congruence in the functionally equivalent elements in fore and hind limbs than in the serially homologous elements. A growth sequence, with decreasing regression coefficients from proximal to distal, was observed in both species under study. This proximo-distal growth sequence is assumed to be ancestral in the ontogeny of eutherian mammals. Different reproductive modes have evolved within eutherian mammals. To test the influence of different life histories on ontogenetic scaling during postnatal growth, one species with altricial juveniles (Tupaia glis) assumed to be the ancestral mode of development for eutherians and one species with derived, precocial young (Galea musteloides) were selected. The growth series covered postnatal development from the first successive steps with a lifted belly to the adult locomotory pattern; thus, functionally equivalent developmental stages were compared. The higher number of allometrically positive or isometrically growing segments in the altricial mammalian species was interpreted as a remnant of the fast growth period in the nest without great locomotor demands, and the clearly negative allometry in nearly all segments in the precocial young was interpreted as a response to the demand on early locomotor activity. Different life histories seem to have a strong influence on postnatal ontogenetic scaling; the effects of the developmental differences are still observable when comparing adults of the two species.

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PubMed2002

Functional morphology of the hindlimb of tupaiids (Mammalia, Scandentia) and its phylogenetic implications.

In this study, the hindlimb of 12 species of tupaiids was analyzed functionally and compared to that of primates, dermopterans, and chiropterans. Many aspects of the tupaiid hindlimb vary in relation to differential substrate use. These differences include width of the ilium, shape of the acetabulum, size of the anterior inferior iliac spine, size of the greater and third trochanters, depth of the femoral condyles, shape of the patellar groove, and size of the tibial tuberosity. The hindlimb of the arboreal Ptilocercus lowii, the only ptilocercine, is better adapted for arboreal locomotion, whereas that of tupaiines is better adapted for rapid terrestrial (or scansorial) locomotion. The hindlimb of Ptilocercus seems to be habitually flexed and has more joint mobility, a condition necessary for movement on uneven, discontinuous arboreal supports. The tarsus of Ptilocercus facilitates inversion of the foot and its grasping hallux is capable of a great range of abduction. Tupaiines, on the other hand, are characterized by more extended hindlimbs and less mobility in their joints. These restricted joints limit movements more to the parasagittal plane, which increases the efficiency of locomotion on a more even and continuous surface like the ground. The hindlimb of tupaiines is adapted for powerful flexion and extension. Even the most arboreal tupaiines remain similar to terrestrial tupaiines in their hindlimb morphology, which probably reflects the terrestrial ancestry of Tupaiinae (but not Tupaiidae). Many attributes of the tupaiid hindlimb, especially those of the foot, reflect the arboreal ancestry of Tupaiidae and it is proposed that the ancestral tupaiid was arboreal like Ptilocercus. Also, compared to the hindlimb character states of tupaiines, those of Ptilocercus are more similar to those of other archontans, and it is proposed that the hindlimb features of Ptilocercus are primitive for the Tupaiidae. Hence, Ptilocercus should be considered in any phylogenetic analysis that includes Scandentia.

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PubMed2002

Functional morphology of the forelimb of tupaiids (Mammalia, Scandentia) and its phylogenetic implications.

In this study, the forelimb of 12 species of tupaiids was analyzed functionally and compared to that of other archontan mammals. Several differences that relate to differential substrate use were found in the forelimb morphology of tupaiids. These differences included shape of the scapula, length and orientation of the coracoid process, size of the lesser tuberosity, shape of the capitulum, length of the olecranon process, and shape of the radial head and central fossa. The forelimb of the arboreal Ptilocercus lowii, the only ptilocercine, is better adapted for arboreal locomotion, while that of tupaiines is better adapted for terrestrial (or scansorial) locomotion. While the forelimb of the arboreal Ptilocercus appears to be habitually flexed and exhibits more mobility in its joints, a necessity for movement on uneven, discontinuous arboreal supports, all tupaiines are characterized by more extended forelimbs and less mobility in their joints. These restricted joints limit movements more to the parasagittal plane, which increases the efficiency of locomotion on a more even and continuous surface like the ground. Even the most arboreal tupaiines remain similar to their terrestrial relatives in their forelimb morphology, which probably reflects the terrestrial ancestry of Tupaiinae (but not Tupaiidae). The forelimb of Urogale everetti is unique among tupaiines in that it exhibits adaptations for scratch-digging. Several features of the tupaiid forelimb reflect the arboreal ancestry of Tupaiidae and it is proposed that the ancestral tupaiid was arboreal like Ptilocercus. Also, compared to the forelimb character states of tupaiines, those of Ptilocercus are more similar to those of other archontans and it is proposed that the attributes of the forelimb of Ptilocercus are primitive for the Tupaiidae. Hence, Ptilocercus should be considered in any phylogenetic analysis that includes Scandentia.

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PubMed1997

Unusual nature and possible evolutionary implications of the male vesicular gland secretion in the tree shrew, Tupaia glis.

BACKGROUND: Whereas the secretion of the male vesicular gland in most mammals is amorphous, that of the tree shrew, Tupaia glis, was observed to be stored as globules. METHODS: Vesicular and prostate glands from Tupaia, fixed in glutaraldehyde and osmium, were studied in the light and electron microscopes. Other materials considered included the Tupaia ejaculate produced by electroejaculation and, for comparative purposes, sections of the vesicular gland from a dermopteran, the flying lemur. RESULTS: The vesicular gland epithelium in Tupaia secretes small granular aggregates and occasionally a denser aggregate that is associated with cells having obvious apical Golgi lamellae. In the alveolar lumen, these aggregates unite with others to form, respectively, granular and some dense globules of up to approximately 15 mu in diameter, which appear as such in semen produced by electroejaculation. In contrast to the prostate, however, precursor secretion vesicles were rare in the vesicular epithelium. Although poorly fixed, the vesicular gland secretion from a flying lemur also appeared to form globules. CONCLUSIONS: Although it is unlike the homogeneous secretion elaborated in most mammals, including primates and insectivores, the globular product of the Tupaia vesicular gland seems comparable to that in a variety of mega- and microbats, among representative species of which it appears to provide the bulk material for the vaginal copulation plug. Because a museum specimen examined here also indicates its occurrence in a flying lemur, the globular vesicular gland secretion common to Tupaiidae, to at least some Mega- and Microchiroptera, and apparently to Dermoptera may provide a soft tissue feature of some value in the cladistic approach to phylogenetic reconstruction within the Archonta. Anat.

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PubMed1981

Function of the mandibular tooth comb in living and extinct mammals.

Among the most interesting mammalian dental specialization is the mandibular 'tooth comb' or 'tooth scraper' that evolved independently in certain primates and other mammals. Its occurrence is most widely known in lemurs and lorises, where it is comprised of the long, slender, procumbent incisors (one or two pairs) and incisiform canines (Fig. 1). In non-primates to canines are not incorporated into the comb. Some tree shrews (Tupaiidae) possess a tooth comb consisting of the four central incisors, and some early Tertiary arctocyonid condylarths had a similar structure composed of all six lower incisors. The extant flying lemurs (Dermoptera: Cynocephalus) also have a dental 'comb' but it is very different from the ones already mentioned, consisting of two pairs of pectinate incisors, each tooth modified into a comb with as many as 15 tines. This condition, although sometimes said to be similar to that in lemurs, is unique to Cynocephalus. One of the principal functions of the tooth comb in primates is to comb the fur, and we present here indirect evidence that condylarths used this structure in the same way, millions of years before tooth combs evolved in prosimians. We also show that the comb-like incisors of Cynocephalus, contrary to popular belief, probably do not function to comb the fur.

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PubMed1982

Anatomy and function of the reproductive tract in the captive male tree shrew (Tupaia belangeri).

The reproductive anatomy of the male tree shrew (Tupaia belangeri) was examined and compared with other Tupaiidae. The testes are located prepenially in a pigmented scrotum which is fused to the base of a pendulous penis. The terminal portion of the vas deferens is differentiated into an ampullary gland and joins the duct of the seminal vesicle to form a short ejaculatory duct. The prostate is a compact bilateral body drained by a main collecting duct. In the aggregate, these features indicate that the reproductive system in Tupaia is primate in character. Testicular function in tree shrews is affected by both social and seasonal factors. When males were housed communally, the majority exhibited testicular degeneration accompanied by a loss in the weight and fructose content of the seminal vesicles and in pigmentation of the scrotum. These changes may be due to the presence of dominant conspecifics since animals kept in isolation undergo normal sexual development. Animals captured throughout the year and isolated show seasonal fluctuations in androgenic and spermatogenic function. Reproductive capacity is maximal during the winter and minimal during the summer. Local environmental factors appear to regulate reproductive function so that the greatest number of births occur during the dry season.

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PubMed2006

Movement trajectories and habitat partitioning of small mammals in logged and unlogged rain forests on Borneo.

1. Non-volant animals in tropical rain forests differ in their ability to exploit the habitat above the forest floor and also in their response to habitat variability. It is predicted that specific movement trajectories are determined both by intrinsic factors such as ecological specialization, morphology and body size and by structural features of the surrounding habitat such as undergrowth and availability of supportive structures. 2. We applied spool-and-line tracking in order to describe movement trajectories and habitat segregation of eight species of small mammals from an assemblage of Muridae, Tupaiidae and Sciuridae in the rain forest of Borneo where we followed a total of 13,525 m path. We also analysed specific changes in the movement patterns of the small mammals in relation to habitat stratification between logged and unlogged forests. Variables related to climbing activity of the tracked species as well as the supportive structures of the vegetation and undergrowth density were measured along their tracks. 3. Movement patterns of the small mammals differed significantly between species. Most similarities were found in congeneric species that converged strongly in body size and morphology. All species were affected in their movement patterns by the altered forest structure in logged forests with most differences found in Leopoldamys sabanus. However, the large proportions of short step lengths found in all species for both forest types and similar path tortuosity suggest that the main movement strategies of the small mammals were not influenced by logging but comprised generally a response to the heterogeneous habitat as opposed to random movement strategies predicted for homogeneous environments. 4. Overall shifts in microhabitat use showed no coherent trend among species. Multivariate (principal component) analysis revealed contrasting trends for convergent species, in particular for Maxomys rajah and M. surifer as well as for Tupaia longipes and T. tana, suggesting that each species was uniquely affected in its movement trajectories by a multiple set of environmental and intrinsic features.

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PubMed1995

Rabl orientation of CENP-B box sequences in Tupaia belangeri fibroblasts.

The chromosomes of the tree shrew Tupaia belangeri exhibit highly localized CENP-B box sequences in the centromeric regions of most chromosomes. Telomeric sequences are present at the ends of all chromosomes and, in addition, at specific interstitial chromosomal sites that likely represent remnants of ancestral telomeres. This suggests that Robertsonian and tandem chromosome fusion events have occurred in the karyotypic evolution of Tupaiidae. In Tupaia skin fibroblasts CENP-B boxes are almost always clustered together at one pole of the interphase nucleus, whereas the telomeric domains are relatively evenly distributed throughout the whole nuclear volume. The observed orientation of the centromeres is reminiscent of the Rabl polarization of chromosomes; this is the first mammalian cell substrate in which such an higher-order chromosomal organization has been observed. CENP-B box sequences are found in several other mammalian species. The implications for recent parallel evolution of CENP-B binding motifs and concerted evolution of these sequences are discussed.

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PubMed1979

"The diencephalon of Ptilocercus lowii (pen-tailed tree-shrew)".

The pen-tailed tree-shrew (Ptilocercus lowii) has been regarded by Le Gros Clark (1926), and Martin (1968) to possess more primitive morphological and to a certain extent, neuro-anatomical characteristics than the other tree-shrew species belonging to the sub-family Tupaiinae. Investigations have been carried out on the diencephalon of Ptilocercus lowii which has not been completely done by Le Gros Clark and other workers since 1926, to find out whether the diencephalon has actually undegone any phylogenetic changes that should be more advanced than those of the Insectivora or remain more primitive than that of the Tupaiinae. The diencephalic structure that show the most significant phylogenetic features which differe Ptilocerecus from Tupaia are observed in the anterior, dorsolateral and ventrolateral thalamic groups, and the geniculate bodies. The nucleus anteroventralis is, by comparison, much smaller and poorly differentiated from the nucleus anteromedialis. The nucleus anterodorsalis is also comparably large and does not reach the dorsal surface of the thalamus as it does in the primates. The midline nuclei do not show any significant differences, except the notably larger size of nucleus parataenialis in Ptilocercus. The nucleus mediodoralis is small and indifferentiated although it does show some incipient signs of cellular differentiation. The nucleus centralis lateralis is well developed; its inferior (ventral) part is larger than its superior part which is the better developed of the two parts in the tupaiids and primates. The nucleus centrum medianum appears to be very small and forms only a lateral extension of the nucleus parafascicularis. The ventrolateral thalamic group basically consists of nuclei ventrales anterior, lateralis and posterior without intermediate or transitional zones as found in Tupaia and Primates. The nucleus pretectalis is the largest and the best developed of all the elements of the posterior thalamic nuclear group. The lateral geniculate nucleus is not differentiated into laminae like that in Tupaia and Primates; it is merely a homogeneous structure that appears to be smaller in size that the pregeniculate and medial geniculate nuclei. The medial geniculate nucleus is large in proportional size of the whole thalamus and appears to be well differentiated cellularly into several small parts. No remarkable changes are noted in the epithalamus, subthalamus and hypothalamus. However, the nucleus ventromedialis appears to be the most outstanding structure in the infundibular region of the hypothalamus. The mammillary region is of a simpler construction in Ptilocercus than in Tupaia; it does not protrude from the ventral surface of the hypothalamus. In the light of these findings, the phyletic status of Ptilocercus in the family Tupaiidae is discussed.

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