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PubMed1977

The role of movement in the development of a digital flexor tendon.

D-tubocurarine was injected into the air sac of 8-day chick embryos to prevent movement of the digits of the hind limb. The embryos were paralyzed from the tenth to the eighteenth day, when the experiment was terminated. The immobilization of the flexor digitorum profundus tendons in the tarsus resulted in a loss of specialized structures around and on this tendon, as determined by light and electron microscopy. Specialized areas observed in the normal chick (synovial cavity, fibrocartilaginous area, and elastic vinculum) failed to form, as a result of the paralysis of the digit. Several authors have shown previously that movement is a requirement for the molding and maintenance of joint cavities in vivo, in ovo and in vitro (see text for references). We have shown that movement of the tendon is required to produce a functional tendon apparatus in the embryo and predict that movement is also required for regeneration after injury.

Animals↗
PubMed1985

An autosomal dominant syndrome of short stature with mesomelic shortness of limbs, abnormal carpal and tarsal bones, hypoplastic middle phalanges, and bipartite calcanei.

This paper describes seven persons in a family affected with an autosomal dominant syndrome of short stature with mesomelic shortness of upper and lower limbs, abnormal carpal and tarsal bones, hypoplastic or absent middle phalanges of hands and feet, and delayed coalescence of bipartite calcanei. All affected relatives are of normal intelligence, are free of eye problems, and have a normal skull, spine, shoulders, and hips. The digits of the hands and feet are short, broad, and angulated. The hypoplastic or absent middle phalanges effectively result in one interphalangeal joint for each digit, with decreased mobility. The bones of the carpus and tarsus coalesce with increasing age. None of the previously described syndromes or brachydactylies encompasses the findings noted in this kindred.

Abnormalities, Multiple↗
PubMed1986

A distinct lethal neonatal chondrodysplasia with snail-like pelvis: Schneckenbecken dysplasia.

We describe the clinical, radiographic, histopathologic, and ultrastructural features of a distinct neonatal lethal chondrodysplasia inherited as an autosomal recessive trait. The characteristic radiographic findings consist of flattened, hypoplastic vertebral bodies; short ribs; hypoplastic iliac bones with "a snail-like" configuration; short, broad long-bones with dumbbell-like appearance; short and wide fibula; and precocious ossification of the tarsus. Chondro-osseous histology is characteristic with hypervascularity, increased cellular density, and normal size chondrocytes with a centrally located round nucleus and absence of lacunar space. Because of the snail-like radiographic appearance of the pelvis in this disorder, we propose the name "Schneckenbecken dysplasia" (ie, German for snail pelvis).

Dwarfism↗
PubMed1995

Bilateral asymmetry in bone weight at various skeletal sites of the rat.

BACKGROUND: Morphological and functional asymmetry in the limbs has generally been regarded as a human characteristic that is of genetic or of both genetic and environmental origin. The aim of this study was to determine the presence of lateral dominance in bone weight of the forelimb of the rat. METHODS: Wistar rats (77) were used, 45 controls and 32 experimental animals, implanted with a steel weight subcutaneously under the right forelimb. Bones examined for bilateral asymmetry in bone weight were the mandibula, the bones of fore- and hindlimbs, calcaneus, and talus of the tarsus. The weight of each dry bone was measured to the nearest milligram. RESULTS: Significant bilateral asymmetry in the forelimb was evident in male and female rats, with the left side having more bone mass than the right. Bilateral differences were more pronounced in the females than the male rats. Greater asymmetry was evident in the experimental group compared to the control rats. CONCLUSIONS: These findings demonstrate that asymmetry is present not only in humans, but also in lower animals such as rats. Greater asymmetry in the experimental rat group is indicative of the influence of environmental factors or physical stress on asymmetry. We conclude that genetics might control the development of asymmetry, but physical stress may alter the functional expression of the asymmetry.

Animals↗
PubMed2001

Pretarsal fat compartment in the lower eyelid.

It is generally accepted that there are three infraorbital fat regions in the lower eyelid; medial, central, and lateral compartments. However, removing only the fat in the lateral compartment does not remove the bulge just below the eyelashes, which is caused by another fat pad. The aim of this study was to describe the anatomy of the pretarsal fat compartment and to demonstrate its clinical implications in lower lid blepharoplasty. Ten cadavers (total 20 lower eyelids) were studied. A skin-muscle flap was reflected to expose the soft pretarsal structures. A small stab incision was made on the lateral portion of the sac containing fat on the tarsus. Methylene blue dye was injected into the sac. Specimens were fixed and sagittal sections in four different planes were prepared for histological analysis. The injected dye remained within the sac and demarcated it as a pear or cone shaped structure. This encapsulated fat compartment sits on the lateral half of the tarsal plate above the lateral compartment fat. Auxillary or submuscular fat is well known. This study, however, designates the pretarsal fat as "encapsulated" in a compartment instead of being unbound. We have named it the "pretarsal fat compartment." Histologically, orbital septal fibers separate "pretarsal fat" from lateral infraorbital fat. It is recommended that fat in the pretarsal fat compartment be removed during lower lid blepharoplasty in order to alleviate the bulge or knoll of the skin just below the lower eyelashes.

Adipose Tissue↗
PubMed1986

Spiking local interneurones in the mesothoracic ganglion of the locust: homologies with metathoracic interneurones.

Two bilaterally symmetrical groups of spiking local interneurones have been characterized in the mesothoracic ganglion of the locust. The cell bodies of one group, the "midline group," lie at the ventral midline. Their primary neurites run in the ventral loop of ventral commissure II to form extensive branches in the neuropile of one-half of the ganglion. A dorso-ventral process in the perpendicular tract links two distinct fields of branches, one ventral and consisting of numerous fine branches of a uniform texture that arise from stout secondary neurites, and the other more dorsal consisting of fewer branches of a varicose appearance. Cell bodies of the second, the "anterior-lateral" group, lie close to the lateral edge of an anterior connective. Their primary neurites run in a more anterior ventral commissure and their neuropilar branches are divided into two fields by a process in a more anterior dorso-ventral tract. Within the two groups, each interneurone has its own distinctive shape that is an elaboration on these basic plans. Each interneurone also has its own characteristic physiology, being excited by a particular array of mechanoreceptors on the middle leg on the same side of the body as its neuropilar branches. The receptive fields of the interneurones, defined in this way, can be extensive and cover a particular surface of all parts of the leg, or restricted to one surface of, for example, the tarsus. These interneurones therefore bear a striking resemblance to two groups of spiking local interneurones in the adjacent segmental ganglion of the metathorax.

Action Potentials↗
PubMed1987

The morphology of a population of thoracic intersegmental interneurones in the locust.

A population of intersegmental interneurones with axons extending from the meso- to the metathoracic ganglion of the locust is described. They receive specific mechanosensory inputs from one mesothoracic leg. Their cell bodies are in group at the posterior of the mesothoracic ganglion, lying over the lateral base of each connective, and their primary neurites emerge in one of four bundles. Their mesothoracic branches are ipsilateral to the cell bodies and the leg from which they receive inputs. Each interneurone has two to six mesothoracic secondary neurites that divide and form a dense field of arborizations in specific regions of the neuropil so that each individual interneurone has a characteristic shape that is an elaboration of a basic and common plan. An interneurone excited by tibial campaniform sensilla and tarsal hair afferents branches in the intermediate neuropil and the ventral association center where the afferents from these receptors also project. An interneurone excited by proprioceptive inputs from the tarsus arborizes in the dorsal and intermediate neuropils, lateral to the ventral intermediate and ventral median tracts, in the same area as the proprioceptors afferents. An interneurone inhibited by proprioceptive inputs from the tibia (and wing) arborizes only in the dorsal neuropil, where there are no afferent projections. Some interneurones have one to three axonal branches with sparse and varicose side branches in the mesothoracic ganglion, which resemble the metathoracic axonal branches. The metathoracic axonal branches are mostly restricted to the dorsal neuropil and the dorsal part of the intermediate neuropil where local non-spiking interneurones and motor neurones controlling movements of the hind leg also project. The overlap between the branches of the sensory afferents and the intersegmental interneurones in the mesothoracic ganglion and between those of the nonspiking local interneurones or motor neurones and intersegmental interneurones in the metathoracic ganglion suggest that these interneurones are responsible for transferring information about the action of one leg to an adjacent leg.

Animals↗
PubMed1990

Morphology of a population of mechanosensory ascending interneurones in the metathoracic ganglion of the locust.

A population of ascending interneurones with cell bodies in the metathoracic ganglion of the locust is described. Interneurones are characterised by their morphology (revealed by intracellular cobalt injection) and by their physiological responses to afferent stimulation. All interneurones have their somata in the ventral cortex of the ganglion, in an area just posterior to the medial tracheae. On the basis of gross morphology the interneurones can be divided into three groups: (1) those that have a main area of fine neurites ipsilateral to the soma and an ipsilateral ascending axon; (2) interneurones that also have their main neurites ipsilateral to the soma but have a contralateral ascending axon, and (3) interneurones that have their main stimulation of sensory receptors on the hind leg ipsilateral to the main neurites. Interneurones receiving excitatory inputs from tactile hairs on the hind leg have branches in the most ventral neuropil, whereas interneurones receiving input from leg proprioceptors have branches in the more intermediate and dorsolateral neuropil. The branching pattern of an interneurone and the size and position of the receptive field on the leg are correlated. Interneurones with restricted branching patterns have restricted receptive fields. The position of the ventral branching reflects the position of the receptive field on the leg. An interneurone with a receptive field restricted to the femur has ventral branches in an anterior position in the ganglion; an interneurone with a receptive field restricted to the tarsus has ventral branches in a more posterior position.

Animals↗
PubMed1991

Morphology and somatotopic organisation of the central projections of afferents from tactile hairs on the hind leg of the locust.

The morphology and organisation of the central projections of tactile hair afferents from the hind leg of the locust, Schistocerca gregaria, were examined by staining individual hair afferents. Each tactile hair on the femur, tibia, and tarsus is innervated by a single sensory afferent, which projects to the ipsilateral half of the metathoracic ganglion. Afferents arborize in the ventralmost and lateral ventral association centres (vVAC and lVAC). The projections are organised somatotopically in a map with three axes, according to the position of the hair on the leg. First, proximo-distal: afferents from hairs on the proximal leg segments project more anteriorly than do those from hairs on distal leg segments. Moreover, on any given segment the afferents from the more proximal hairs project more anteriorly than do the afferents from the distal hairs. Second, antero-posterior: afferents from hairs on the posterior surface of the leg project more medially than do afferents from anterior hairs. Third, dorso-ventral: afferents from hairs on ventral parts of the leg project more ventrally than do afferents from the dorsal hairs. The afferents from posterior and anterior hairs project to an area between the central projections from dorsal hairs and ventral hairs. The position of a projection within the map is dependent upon the location of the hair on the leg and not the peripheral routes taken by the axon of its afferent to reach the ganglion.

Animals↗
PubMed1993

Correlation between the receptive fields of locust interneurons, their dendritic morphology, and the central projections of mechanosensory neurons.

The relationships between the morphology and receptive fields of local and intersegmental interneurons that process mechanosensory information from a hindleg of the locust have been analysed. Sensory neurons from tactile hairs project to ventral areas of neuropil in the metathoracic ganglion where they form a 3-dimensional somatotopic map of a hindleg. By contrast, sensory neurons from a proprioceptor at the femoro-tibial joint (the femoral chordotonal organ) project to lateral and more intermediate areas of neuropil and have no branches in the most ventral regions of neuropil. Particular local and intersegmental interneurons respond to stimulation of specific arrays of hairs on a hindleg, or to movements of particular joints. Their receptive fields are defined, in part, by the patterns of excitatory, monosynaptic connections made by these afferents. Each interneuron has a characteristic receptive field and a characteristic morphology defined by its array of branches in the regions of neuropil containing the projections of the afferents that provide its monosynaptic inputs. Interneurons with inputs exclusively from tactile hairs have branches in the most ventral regions of neuropil, while those with exclusively proprioceptive inputs have branches only in more intermediate levels of neuropil. Interneurons with extensive receptive fields from tactile hairs also have extensive areas of branching within the ventral neuropil. Interneurons with receptive fields restricted to particular regions of the leg have branches restricted to the ventral region of neuropil containing the projections of afferents from that part of the leg. Thus, interneurons with inputs only from hairs on the tarsus have branches in the posterior region of neuropil corresponding to the projections of the tarsal afferents, while interneurons with receptive fields on the femur have branches in more anterior regions of neuropil corresponding to the projections of the femoral hair afferents. Interneurons with receptive fields on the tibia have branches in neuropil between the tarsal and femoral projections.

Afferent Pathways↗
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.

Animals↗
PubMed2002

Inositol 1,4,5-trisphosphate transduction cascade in taste reception of the fleshfly, Boettcherisca peregrina.

The role of an inositol 1,4,5-trisphosphate (IP3)-mediated transduction cascade in the response of taste receptor cells of the fleshfly Boettcherisca peregrina was investigated by using the following reagents: neomycin (an inhibitor of IP3 production), U73122 (an inhibitor of phospholipase C), adenophostin A (an agonist of the IP3-gated channel), IP3, ruthenium red (a blocker of the IP3-gated channel), and 2-aminoethoxydiphenylborate (2-APB; an antagonist of the IP3-gated channel). For introduction into the receptor cell, the reagents were mixed with a detergent, deoxycholate (DOC). After treatment with neomycin + DOC or U73122 + DOC, the response of the sugar receptor cell to sugars was depressed compared with responses after treatment with DOC alone. During the treatment of adenophostin A + DOC, the response of the sugar receptor cell was elicited. After treatment with IP3 + DOC, the response of the sugar receptor cell to sugars and to amino acids was apparently enhanced. When taste stimuli were administered in the presence of ruthenium red or 2-APB, the response of the sugar receptor cell to glucose were inhibited. The expression of genes for substances involved in the IP3 transduction cascade, such as G protein alpha subunit (dGqalpha), phospholipase C (norpA), and IP3 receptor (itpr), were examined in the taste receptor cell of the fruitfly Drosophila melanogaster by using the pox-neuro70 mutant (poxn70), which lacks taste receptor cells. The expressed levels of dGqalpha and itpr in the tarsus of poxn70 mutant flies were reduced compared with those of wild-type flies. These results suggest that the IP3 transduction cascade is involved in the response of the sugar receptor cell of the fly.

Adenosine↗
PubMed1979

The structure and function of serially homologous leg motor neurons in the locust. I. Anatomy.

Twenty-one prothoracic and 17 mesothoracic motor neurons innervating leg muscles have been identified physiologically and subsequently injected with dye from a microelectrode. A tract containing the primary neurites of motor neurons innervating the retractor unquis, levator and depressor tarsus, flexor tibiae, and reductor femora is described. All motor neurons studied have regions in which their dendritic branches overlap with those of other leg motor neurons. Identified, serially homologous motor neurons in the three thoracic ganglia were found to have: (1) cell bodies at similar locations and morphologically similar primary neurites (e.g., flexor tibiae motor neurons), (2) cell bodies at different locations in each ganglion and morphologically different primary neurites in each ganglion (e.g., fast retractor unguis motor neurons), or (3) cell bodies at similar locations and morphologically similar primary neurites but with a functional switch in one ganglion relative to the function of the neurons in the other two ganglia. As an example of the latter, the morphology of the metathoracic slow extensor tibiae (SETi) motor neurons was similar to that of pro- and mesothoracic fast extensor tibiae (FETi) motor neurons. Similarly the metathoracic FETi bears a striking resemblance to the pro- and the mesothoracic SETi. It is proposed that in the metathoracic ganglion the two extensor tibiae motor neurons have switched functions while retaining similar morphologies relative to the structure and function of their pro- and mesothoracic serial homologues.

Animals↗
PubMed2002

Implantation of MNNG crystals into a Triturus intact limb affects mitotic and labeling indices, regeneration rate, and morphogenesis in the contralateral, regenerating limb.

Experimental administration of chemical carcinogens to various mammals is highly effective in inducing malignant tumors. In contrast, treatment of regeneration-competent animals even with much higher doses of the same drugs only exceptionally leads to tumor-like growth. Usually, carcinogenic materials implanted or injected into a regenerating limb of urodele amphibia interfere with the regenerative process and frequently lead a). to growth retardation or arrest of regeneration, b). to development of a great variety of abnormal regenerates, and c). to generation of accessory, limb-like structures. Autonomous or experimental incidence of carcinogenesis is extremely low in animals endowed with strong regenerative capabilities. Of exceptional biological significance is the fact that such induced tumors usually regress spontaneously. This unique property of the regeneration-competent animals to resist carcinogenesis provides opportunities to compare non-cancerous alterations in the differentiated state of adult cells to those occurring in neoplasia. The mode of action of the chemical carcinogens on limb regeneration has not yet been clarified with certainty at the cellular and the molecular level. Several scientists claim that the above-mentioned effects might be attributed to local toxic influences of the drugs; therefore the present study was designed to investigate whether the administration of the carcinogen MNNG can affect cell proliferation, histogenesis, and morphogenesis at a region distant from the site of its implantation, even after a relatively long time period. To this end, 40 animals of the species Triturus cristatus had their right hindlimb surgically removed at the distal zeugopod. Then, a small microcrystal (approximately 5 micro g) of MNNG was inserted under the ventral aspect of the skin of the left tarsus in 20 of these animals (groups T and A; see below). Two months later, nine of the MNNG-treated animals were injected intraperitoneally with tritiated thymidine. After 2 h, six of these animals had their right hindlimb amputated at the distal zeugopod, whereas the rest were left to regenerate. The results were evaluated by camera lucida drawings, clearing in methyl benzoate, classical histology, and autoradiography. It was revealed that administration of MNNG at a somatic region (left hindlimb) reduces DNA synthesis and mitosis at a distant place (right hindlimb) even 2 months after MNNG implantation. Despite this, the rate of limb elongation is not substantially reduced. Classical histology revealed normal tissue structure throughout. All regenerated limbs displayed several teratogenic abnormalities.

Amputation, Surgical↗
PubMed2000

The effects of age and previous experience on social rank in female red junglefowl, Gallus gallus spadiceus.

Social rank can influence lifetime reproductive success and therefore fitness. We examined the effects of morphology, age, previous social experience and aggressiveness on social rank in all-female flocks of red junglefowl. None of the morphological characters measured (mass, tarsus length, comb height or comb length) appeared to play a role in determining rank. Older females were not more likely to be dominant, while previous social experience and aggression levels were both important in dominance determination. Flock-experienced hens were more likely to be dominant as were more aggressive individuals. Red junglefowl females most likely use a combination of characters to establish social order in a newly formed flock. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1993

Octopod, a homeotic mutation of the moth Manduca sexta, affects development of both mesodermal and ectodermal structures.

Several aspects of leg development in the moth Manduca sexta were examined using the homeotic mutation Octopod (Octo). This mutation causes a transformation of the ventral epidermis of the first abdominal segment (A1) to that of the third thoracic segment (T3), resulting in the presence of thoracic-like legs on A1. The degree of transformation of A1 is variable, ranging from bumps on the cuticle to fully segmented thoracic-like legs. In the normal thoracic legs, clusters of undifferentiated cells known as differentiation centers are located around the coxal-trochanteral, femoral-tibial, and tibial-tarsal joints. The adult thoracic legs develop from the differentiation centers at metamorphosis. The homeotic legs of the Octopod larvae also have differentiation centers at comparable positions in the homeotic leg. As a result, the number of leg segments in a mutant adult is correlated with the number of segments and differentiation centers that animal had in its larval homeotic leg. Our data suggest that the differentiation center located at the coxal-trochanteral joint forms the adult coxa and trochanter, the center at the larval femoral-tibial joint the adult femur and tibia, and the differentiation center at the larval tibial-tarsal joint the adult tarsus. Homeotic larval legs which include at least a femur have supernumerary muscles, while adult homeotic legs rarely show discrete muscle. The homeotic larval muscles appear to have thoracic identities, based on their attachment points and the timing of their degeneration at the larval-pupal transition. They are innervated by a motoneuron that is normally present in A1 where it innervates the ventral lateral external muscle (VLE). In mutant animals, the same motoneuron innervates all of the homeotic muscles and the VLE. We consider possible mechanisms underlying the development of homeotic muscles and their innervation. At the larval-pupal transition, the VLE in mutant animals degenerates at its normal time, which is 3 days after the degeneration of the homeotic muscles. Thus, despite their common innervation, the two muscle types degenerate according to their own schedules, indicating that the developmental fates of the muscles are not dictated by their innervating neuron but are intrinsic to the muscles themselves.

Animals↗
PubMed1995

Time- and concentration-dependent response of the Drosophila antenna imaginal disc to Antennapedia.

The response of the antenna imaginal disc to ectopic Antennapedia gene expression was explored in a heat shock Antennapedia (hsAntp) transgenic strain and in strains doubly transgenic for hsAntp and downstream enhancer trap targets. The distal to proximal changes in morphological transformation in response to Antennapedia product at different developmental stages were correlated with changing expression patterns of transgene targets from antenna to leg-like patterns. Dose-response studies indicated changing thresholds of response to Antennapedia. At particular stages and doses of Antennapedia product, cell differentiation of leg bristles was uncoupled from transformation of the third antennal segment to tarsus. The results suggest that determination for bristle type does not depend on a prior determination decision for organ type. The results also provide an avenue for exploring the nature of "competence" at cellular and molecular levels.

Animals↗
PubMed1988

Correction of severe upper eyelid entropion.

Lid splitting procedures have been described a long time ago. Despite repeated descriptions by various authors, the method is not widely known. We use a bare-tarsus technique, omitting any grafting. In addition, we found radial incisions at the nasal and temporal edges of the anterior lamella advantageous, as the often superimposed blepharospasm is abolished by the weakening of the tarsal part of the orbicularis muscle. Also, there is then less tendency for the recessed anterior lamella to creep back down to the lid margin.

Blepharospasm↗