Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Forelimb”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources
PubMed1996

Functional cooperation between the non-paralogous genes Hoxa-10 and Hoxd-11 in the developing forelimb and axial skeleton.

The Abdominal B-related Hoxa-10 gene displays similar expression patterns in the differentiating forelimbs and hindlimbs of the mouse, with preferential expression around the humeral and femoral cartilages and more diffuse expression in distal regions. We found that a targeted disruption of Hoxa-10 has almost no effect in the forelimbs, while it affects the proximal hindlimb skeleton. The alterations were located along the dorsolateral side of the femur (labium laterale), with an enlargement and distal shift of the third trochanter, a misshapen lateral knee sesamoid, a supernumerary 'ligament' connecting these structures and an occasional duplication of the femoral trochlea. Some Hoxa-10-/- mutant mice developed severe degenerative alterations of the knee articulation upon ageing. Viable Hoxa-10/Hoxd-11 double mutant mice were produced by genetic intercrosses. The compound mutation resulted in synergistic forelimb phenotypic alterations, consisting of: (i) an exacerbation of Hoxd-11-/- phenotypic traits in the carpal and digital region, e.g. more pronounced truncations of the ulna styloid, pyramidal and pisiform bones and of some metacarpal and phalangeal bones and (ii) marked alterations in a more proximal region which is nearly unaffected in Hoxd-11-/- single mutants; the entire radius and ulna were truncated and thickened, with deformations of the ulna proximal extremity. Thus, functional redundancy can occur even between non-paralogous Abdominal B-related Hox genes. The double Hoxa-10/Hoxd-11 mutation also conferred full penetrance to the sacral and caudal vertebrae transformations which are approximately 50% penetrant in Hoxd-11-/- single mutants, revealing that functional cooperation can also occur between non-paralogous Hox gene products in axial skeleton patterning.

Abnormalities, Multiple↗
PubMed1986

Functional metabolic mapping during forelimb movement in rat. I. Stimulation of motor cortex.

The quantitative 14C-deoxyglucose (DG) autoradiographic technique has been used to study changes in cerebral metabolism during forelimb movements induced by graded stimulation of motor cortex. Experiments were directed at studying basic physiologic and anatomic aspects of the metabolic changes. Single shocks caused movement without metabolic change, whereas low-frequency trains caused seizures. Repetitive high-frequency train stimuli of short duration (500 Hz for 20 msec) caused jerk movements coupled with DG uptake in pathways. With stimulation of the forelimb motor zone at frequencies of 15-30/min there was prominent activation of cortical columns and strips in ipsilateral SI, SII, and MII, and contralateral MI and SI. Higher frequencies (120/min) were required to cause significant changes in DG in subcortical circuits. The most prominent changes occurred within a longitudinal corridor in dorsal thalamus and a ventral corridor in second-order sites in basal ganglia. Metabolic activation also occurred in contralateral cerebellum, the cuneate nucleus, and dorsal horn of the cervical spinal cord. Changes in these latter two sites were largely eliminated by removing feedback sensory activity. Stimulation of the forelimb sensory zone activated different sites in caudatoputamen and thalamus but similar zones in midbrain and cerebellum. The magnitude of the metabolic response in distant sites depended on the frequency of cortical stimulation. Different frequency-response relationships in different sites seemed to reflect the nature of the cortical input as well as differential effects of anesthesia. The pattern of the metabolic response was studied by comparing sites of activation with sites of the anatomic projections from motor and sensory cortical zones. 3H- and 14C-labeled amino acids were used to map the site and relative strength of pathways. Results revealed good correlation between the site of anatomic projection and the site of DG uptake but no consistent relationship between the relative strength of a projection and the magnitude of metabolic change within its field. Changes in glucose utilization with metabolic mapping experiments depend on the nature, strength, and frequency of stimulation; the site and nature of anatomic projection; the effects of anesthesia; and the strength of sensory feedback associated with the induced behavior.

Animals↗
PubMed1984

[A study on relation between premotor cortex and forelimb movement: analysis of neuronal activity].

The aim of this study is, first, to examine the existence of topographical organizations in the premotor cortex in monkeys trained rigorously to move his proximal and distal forelimb separately. The second aim is to observe premotor cortex neuronal activity in association with simple movement triggered by sensory signals of three different modalities (visual, auditory, and somatosensory). Premotor cortex was defined as the lateral part of frontal agranular cortex where intracortical microstimulation could not evoke muscle contraction at intensity below 50 microA. Neurons related to the distal forelimb movement formed three foci in the premotor cortex. Neurons related to the proximal forelimb movement distributed widely in the premotor cortex without forming any distinct focus. Movement-related premotor neurons showed less modulation of discharge frequency in association to the movement than motor cortex neurons, and some of them responded selectively to one or two sensory signals triggering the movement. These results suggests that premotor cortex contributes less directly to the execution of simple movements, but may play an important role in controlling or organizing complex movements.

Acoustic Stimulation↗
PubMed1997

Comparative myology of the forelimb of squirrels (Sciuridae).

The musculature of the shoulder, arm, and forearm was studied in 19 genera of squirrels, representing the Pteromyinae (flying squirrels) and all 7 tribes of the Sciurinae (tree and ground squirrels). The objective was to locate derived anatomical features of functional or phylogenetic significance and to determine how much morphological variation underlies the diverse locomotor behavior of squirrels, which includes terrestrial and arboreal bounding, climbing, digging, and gliding. The fossil evidence suggests that arboreality is primitive for squirrels, and in fact tree squirrels appear to represent the primitive sciurid morphology. Ground squirrels are less uniform and exhibit a few derived features, including a clavobrachialis muscle not seen in other squirrels. Pygmy tree squirrels, which have evolved independently in three tribes, exhibit convergence of forelimb anatomy, including the loss or reduction of several muscles in the shoulder and forearm. The forelimb anatomy of flying squirrels is the most derived and differs from that of tree squirrels in details of shoulder, arm, and forearm musculature. Some of these muscular differences among squirrels have phylogenetic significance, being shared by closely related genera, but none has significance above the tribal level. Many of the differences suggest a variety of changes in function that are amenable to further study.

Animals↗
PubMed2000

Caffeine decreases the occurrence of cadmium-induced forelimb ectrodactyly in C57BL/6J mice.

BACKGROUND: Cadmium is a well-known animal teratogen. Caffeine is an alkaloid widely consumed by humans. Interactions between teratogens and nonteratogenic doses of other agents are becoming widely studied, as they may shed light on understanding mechanisms of teratogenicity or possible prevention of teratogenic effects. METHODS: C57BL/6JBK mice were injected intraperitoneally (ip) with cadmium sulfate (Cd) at 0, 1.00 (LDCd), 2.50 (MDCd), or 5.00 (HDCd) mg/kg, immediately followed by subcutaneous (sc) administration of 0 or 50 mg/kg caffeine (CAFF) on gestation day (GD) 9. Fetuses were examined on GD 18 for ectrodactyly and other gross morphological malformations. RESULTS: Amelioration of cadmium-induced forelimb ectrodactyly by CAFF was seen in both the high-dose cadmium (HDCd = 65.4%, HDCd+CAFF = 39.2%) and medium-dose cadmium (MDCd = 46.2%, MDCd+ CAFF = 20.8%) treatment groups (P < 0.025). Bilateral expression of ectrodactyly was also decreased in the presence of caffeine. A statistically significant reduction in Cd-induced abnormalities, including: eye, abdominal, and other skeletal defects, was not seen with caffeine addition, although they did trend downward in the caffeine-supplemented groups. Litter size, fetal weight, fetal mortality, and dam weight also were not affected by co-treatment with caffeine. CONCLUSIONS: This study provides evidence that a subteratogenic dose of caffeine can ameliorate cadmium-induced forelimb ectrodactyly in the Cd-sensitive C57BL/6J inbred mouse strain.

Abnormalities, Drug-Induced↗
PubMed1981

The ability of localized implants of whole or minced dermis to disrupt pattern formation in the regenerating forelimb of the axolotl.

The ability of localized grafts of dermis to alter pattern formation in the regenerating limb of the axolotl was studied. Longitudinal pieces of skin (1/4 of circumference of the limb) were removed from either the anterior or the posterior surface of the upper forelimb. Epidermis was removed by immersion in versene followed by mechanical stripping. The resulting dermis was cross transplanted directly beneath the skin on the opposite side of the limb from which it originated. After 5 days of healing each limb was amputated through the graft at the midpoint of the humerus. High percentages of multiple regenerates resulted. Similar results were obtained when dermis was minced into 1 mm3 fragments prior to cross-transplantation. Freezing or x-raying (2000 rads) the grafts prior to cross-transplantation abolished the effect. Dermis obtained form head skin rarely caused multiple regeneration when implanted into the upper forelimb followed by amputation 5 days later. These results demonstrate that addition of dermis to an intact limb stump profoundly alters pattern formation during regeneration. The effect is dependent upon viable cells that are capable of cell division.

Ambystoma↗
PubMed1983

Forelimb musculature and ligaments in Ateles, the spider monkey.

The forelimb anatomy of Ateles, the spider monkey, is a key factor in its locomotor adaptation because of its extensive use of bimanual suspensory locomotion in addition to climbing and quadrupedal walking (Mittermeier, 1978; and Fleagle and Mittermeier, 1980). The detailed description of the muscles and ligaments of the forelimb of Ateles provided in this paper can be of considerable use not only to primate morphologists interested in both extant and fossil primates but also to functional anatomists. All measurements were made on fresh, unembalmed specimens. Standard anatomical descriptions of the musculature, cross-sectional areas of the muscles, dry weights of muscle bellies, and relative proportions of antagonistic muscles are reported as are the joint ligaments and potential range of motions of the joints. These anatomical data are compared briefly to published data on Alouatta, the howler monkey, which is predominantly a quadruped (Fleagle and Mittermeier, 1980; and Schön Ybarra, 1982).

Aging↗
PubMed1986

Effects of denervation and delayed amputation on forelimb regeneration in Xenopus laevis froglets.

Left forelimbs of postmetamorphic Xenopus laevis froglets were repeatedly denervated prior to and following amputation. Amputations were performed 14, 21, 28, or 42 days after the original denervation. A tissue-regenerative response resulting in the formation of a spike-shaped, heteromorphic outgrowth was found in the sham-denervated and control animals, but dedifferentiation of the stump tissues was not apparent. Tissue-regenerative outgrowths were not observed in the denervated cases; instead, dermal wound healing and stump and scar formation occurred. In both control and experimental cases, however, a periosteal proliferative response to amputation injury led to the development of a greatly thickened periosteum the length of the amputated radius-ulna as well as a cap of cartilage at the distal end of these bones. We conclude from these results that forelimbs of postmetamorphic froglets are incapable of adjusting to a prolonged nerveless state sufficient to allow the normal tissue-regenerative response of spike outgrowth formation.

Animals↗
PubMed1986

The pattern of spinal and medullary projections from a cutaneous nerve and a muscle nerve of the forelimb of the cat: a study using the transganglionic transport of HRP.

The transport of HRP into the spinal cord and medulla in the cat has been examined from a forelimb cutaneous nerve, the lateral superficial radial nerve (LSR), and from the muscle nerves supplying both heads of the forelimb muscle, extensor carpi radialis (ECR). HRP transported by the LSR was widely distributed in the spinal cord throughout laminae I-IV in the vicinity of the root entry zone and from spinal segments T1 to C5. HRP was also transported from the LSR to the medulla where there was intense patchy, discontinuous labelling in the main cuneate nucleus. The pattern of labelling in the cuneate nucleus did not follow any simple somatotopic plan. Exposure of the muscle nerve to HRP led to labelling in the spinal dorsal horn in lamina I, in the deep dorsal horn on the lamina V/VI border, and in lateral and medial lamina VI at sites that contain cells of origin of spinocerebellar tracts. The medial lamina VI label was contiguous with a deposit that extended medially to the central canal. The label in lateral lamina VI was patchy and formed a discontinuous column from T1 to C5. HRP transported by the muscle nerve also produced label in the more ventral regions of the cuneate nucleus where it had a lacy appearance, in part due to its extensive distribution around dendrites. A relatively dense, patchy, and discontinuous deposit of reaction product was also present in the external cuneate nucleus after muscle nerve exposure. This deposit was most intense on the dorsomedial surface of this nucleus, but another, less intense, deposit was also present ventrally.

Afferent Pathways↗
PubMed1987

Forelimb motor cortical projections in normal rats and after neonatal hemicerebellectomy: an anatomical study based upon the axonal transport of WGA/HRP.

Cerebral cortical projections from the forelimb motor cortex, as defined by intracortical microstimulation where movements were evoked at low current intensities (less than 15 microA), were examined in normal rats and in adult rats that sustained neonatal hemicerebellectomy. The distribution pattern of cortical efferent projections in normal rats generally appeared more restricted than previously described. This restricted distribution is attributed to the use of WGA/HRP as the axonal tracing method and to the electrophysiological definition of the injection site as the motor cortex. The observed remodeling of the corticobulbar projections, seen after cerebellar lesions in the young, largely confirmed previous reports. Moreover, no alterations in the laterality of distribution in corticospinal projection were found. Aberrant corticospinal projections were sought in an effort to provide an anatomical basis to a previous description of abnormally low-threshold ipsilateral forelimb responses evoked from the motor cortex in adult rats after neonatal cerebellar lesions. This apparent absence of corticospinal tract remodeling after neonatal hemicerebellectomy suggests that the abnormal responses are mediated by the normal corticospinal pathways. This possibility is discussed in terms of an alteration in the spinal circuits that may change the responsiveness of spinal motoneurons to a given pyramidal discharge.

Animals↗
PubMed1989

Location of forelimb motoneurons in the Japanese toad (Bufo japonicus): a horseradish peroxidase study.

To label the spinal motoneurons innervating the forelimb muscles of the Japanese toad, horseradish peroxidase (HRP) was injected into these muscles or applied to the cut end of the brachial nerves (N. radialis and N. ulnaris). Spatial distribution of the HRP-labeled motoneurons was reconstructed from serial frontal sections of the spinal cord and their location was examined. Motoneurons innervating forelimb muscles were distributed in the lateral cell column from segment 3 to segment 5 of the ipsilateral brachial spinal cord. In the transverse plane of the spinal cord, motoneurons innervating the medial forearm muscles (innervated by N. ulnaris) were located in the more medial part of the lateral cell column, whereas those innervating the lateral forearm muscles and the upper arm muscle (innervated by N. radialis) were located in the more lateral part of the lateral cell column. Along the longitudinal axis of the spinal cord, motoneurons innervating the more anterior (flexor side) forearm muscles were located in the more rostral part of the spinal cord, whereas those innervating the more posterior (extensor side) forearm muscles were located in the more caudal part of the spinal cord. Thus, motoneurons innervating forearm muscles were well organized somatotopically not only in the transverse plane, but also along the longitudinal axis of the spinal cord. Such a somatotopic organization of motoneurons along the longitudinal axis could also be regarded as a functional one; the flexor motoneurons were located rostrally to the extensor motoneurons.

Animals↗
PubMed2002

Vasculature in pre-blastema and nerve-dependent blastema stages of regenerating forelimbs of the adult newt, Notophthalmus viridescens.

Immunocytochemistry utilizing a monoclonal antibody (BV1; blood vessel 1) highly reactive to the vasculature of the adult newt showed that a developing vasculature was present during early, pre-blastema, and early-bud blastema stages of forelimb regeneration in this species. Infusion of Prussian Blue and DiI into the brachial artery further delineated the intactness of this early vasculature. Finally, macroscopic observations of vascular flow underneath the apical epithelial cap (AEC) and microsurgical removal of the AEC and observation of subsequent bleeding buttressed the conclusion that an intact vasculature exists during early nerve-dependent stages of newt forelimb regeneration. The results suggest that this process of neovascular formation is angiogenesis, i.e., the formation of new vessels from pre-existing vessels in the stump. Furthermore, angiogenesis is an ongoing process initiated early after amputation. Blastema cells and the AEC are likely sourcesof factors that stimulate neovascularization.

Animals↗
PubMed1976

The regeneration of brachial nerves of contralateral origin into benervated fused newt forelimbs.

Previous studies involving the end-to-end fusion of the forelimbs of the adult newt have demonstrated that new limbs can regenerate from the transected ends of proximo-distally reversed limb segments. The limb regeneration could only have been initiated by nerve fibers of contralateral origin. The purpose of the present study is to describe histologically the manner in which nerve fibers of contralateral origin regenerate through the junction of fused limbs into the opposite limb. The first sign of nerve regeneration into the opposite limb was observed at eight days post fusion. The nerves crossed over into the opposite, originally denervated limb in a highly dispersed manner. These nerve fibers eventually aggregated, however, either under the skin or within persisting nerve trunks. By 19 days post fusion the nerve fibers had reached the elbow region of the originally denervated limb and by 25 days they were seen at the most proximal extent of the limb. The diameters of the axons seemed smaller than the diameters of regenerating axons observed in non-fused newt forelimbs.

Animals↗
PubMed1979

The interaction of nerves of opposite regenerating polarity in fused newt forelimbs.

Previous studies involving nerve interactions and limb regenerative processes were carried out on adult newts after their forelimbs were amputated through the distal radius and ulna and fused end-to-end. On the basis of limb regeneration results at the junction of the fused limbs, it was postulated that regenerating nerves from each limb (i.e., nerves of opposite polarity) would not invade the foreign territory of the contralateral limb if it were already normally innervated. A direct study of this nerve interaction, however, was not made in this earlier study. The present investigation was designed to obtain direct histological and electrophysiological evidence for the interaction of nerves of opposite regenerating polarity in fused newt forelimbs. The primary objective was to determine how the regenerating nerves would interact in the establishment of innervation territories-first, at the fusion zone, which represents the junction of the normal innervation territories of the nerves of each limb; and secondly, half way up one of the limbs, where interaction would occur in a territory normally innervated by only one of the regenerating nerves. The results showed that when nerves of opposite regenerating polarity approached one another at the junction of the fused limbs a discontinuation of axonal growth occurred; no indication of overlap of nerves into foreign territory was seen. When the nerves were allowed to interact within one of the fused limbs, however, an overlap of nerve fibers and a functional "double innervation" of that limb was demonstrated. These results are discussed in terms of possible mechanisms for the establishment of innervation territories in salamander limbs. The question of nerve-muscle reinnervation specificity is also raised.

Animals↗
PubMed1982

The effect of limiting light to the pineal on the rate of forelimb regeneration in the newt.

Newts with bilaterally amputated forelimbs were exposed to either continuous light (LL), total darkness (DD), or continuous light with the dorsal head epithelium painted with an India ink and Nile blue sulfate mixture (LL-II-NBS) that limited light penetration through the skull to the pineal. The LL-II-NBS animals regenerated their forelimbs more slowly then their counterparts in LL.

Animals↗
PubMed1979

Partial regeneration of the above-elbow amputated rat forelimb. I. Innate responses.

Although a number of recent studies describe the facilitation of limb regeneration by electrical and other forms of stimulation, little is known of innate regenerative capacity in the mammalian limb. The present report describes spontaneous regenerative responses following subtotal forelimb amputation in the young white rat. In one group of animals the forelimb was amputated through the lower humerus and the skin sutured closed. In a second group, adjacent muscle tissue still attached to bone at its origin(s) was interposed between the cut surface of the humerus and the skin. Among animals of the first group (skin closure only) bone growth and limb regenerative responses were generally not observed. Animals of the second group displayed significant elaborations of cartilage and bone at the limb terminus. The appearance and subsequent modification of these tissues suggest that some capacity for limb regeneration exists innately in the young rat and can be more readily evoked than has been recognized heretofore. It is concluded that extant and forthcoming reports of electrically stimulated skeletal tissue growth, repair and regeneration among eutherial mammals should be examined to determine whether reported responses to stimulation represent advances beyond what might be expected from innate replacement processes alone.

Amputation, Surgical↗
PubMed1989

Comparison of the muscle mechanics of the forelimb of three climbers.

The climbing behavior, muscle mechanics, and functional properties of selected forelimb muscles were examined to ascertain how three distantly related mammals may be adapted for climbing. To determine if features of the fox squirrel (Stalheim-Smith: J. Morphol. 180:55-68, '84) are general or unique features for a climber, two distantly related climbers, the raccoon (Procyon lotor) and the opossum (Didelphis virginiana), were studied. Muscle mechanics varied: the elbow flexors of the fox squirrel produced significantly more torque per unit mass than did the corresponding muscles of the opossum except at 80 degrees, but not more than the corresponding muscles of the raccoon. On the other hand, there were no statistically significant differences in torque per unit mass among the elbow extensors of the three climbers. Both elbow flexors and elbow extensor had faster contraction times and were more fatigable in the fox squirrel than in the opossum or in the raccoon. The data suggest that the musculoskeletal characteristics of the forelimbs of climbers vary according to behavioral, and possibly phylogenetic, differences.

Animals↗
PubMed1986

Comparative anatomical analysis of human trisomies 13, 18, and 21: I. The forelimb.

Human trisomies 13, 18, and 21 exhibit specific neuromuscular phenotypes (Pettersen and Bersu, '82) which include a high proportion of neuromuscular forelimb variations, many of which are atavistic in nature (de Beer, '58; Barash et al., '79; Aziz, '81a). In order to test the neuromuscular phenotype, examine the atavistic nature, and analyze the developmental delay of the trisomy forearm musculature, we dissected the forelimbs of five trisomy 13, ten trisomy 18, and two trisomy 21 cases. Our dissections compare favorably with the existing published trisomy cases (Opitz et al., '79; Pettersen and Bersu, '82). Additionally, we found significant differences in the stage at which developmental arrest occurred in trisomies 13 and 18 for the pectoral complex, extensor digitorum profundus, and intrinsic hand musculature. Some of these muscles, which occur normally in nonhuman primates (Cihak, '67, '69; Dunlap et al., '85), also appear briefly in normal human ontogeny (Cihak, '72), constituting further evidence for developmental delay in aneuploids. The disproportionately effected limb tissues also lend support to the evidence for some degree of autonomy in their development in normal individuals. Our observations are consistent with Shapiro's amplified developmental instability model ('83). Aneuploids may be viewed as genetic variants from which much may be learned about normal limb development, how aneuploidy affects dysmorphogenesis, and the kind of information which exists on the duplicated (or monosomic) chromosome.

Adult↗