Ventral Muscles Research Articles

Controlled feeding alleviates the reduced growth associated with spawning in farmed yellowtail (Seriola quinqueradiata)

Abstract Growth initiates sexual maturation in fish but the onset of maturity also leads to a marked loss in body weight. To avoid the growth loss associated with spawning, yellowtail ( Seriola quinqueradiata ) farmers have attempted to restrict the diets of their fish stocks from winter to spring, the period just before the breeding season. This prevents reductions in body weight. In our present study, we show through endocrinological and physiological analyses of harm-cultured yellowtails that the growth of these fish can be regulated through dietary control. Our results indicate that the body weights of a diet restricted yellowtail group gradually increases through the breeding season compared with the controls. Both the body weights and folk lengths of the diet restricted group surpassed the control groups. In the spawning season, the diet restricted group had smaller gonads than the controls in both sexes. However, the gonad somatic index (GSI) rapidly increased in the control group compared with the restricted group and histological observations of the controls further indicated that the testes contained sperm, and that the female gonads contained numerous oocytes that had accumulated yolk. These findings confirm that a restriction of the diet suppresses gonad development during the yellowtail breeding season. The sex steroid hormone, 17α, 20β-diOHprog, was found to be associated with this dietary control of gametogenesis as it showed decreased levels in the restricted groups compared with the controls. To further investigate the functions of 17α, 20β-diOHprog on fish growth, this hormone was administered intraperitoneally to juvenile yellowtails. Implanted fish showed a remarkable increase in body weight compared with the control group and the lipase activities of the dorsal and ventral muscles of 17α, 20β-diOHprog-injected fish were also higher than those in the control group. We conclude from our data that the regulation of the yellowtail diet can control their growth and gametogenesis.

Ectodermal Wnt signaling regulates abdominal myogenesis during ventral body wall development

Defects of the ventral body wall are prevalent birth anomalies marked by deficiencies in body wall closure, hypoplasia of the abdominal musculature and multiple malformations across a gamut of organs. However, the mechanisms underlying ventral body wall defects remain elusive. Here, we investigated the role of Wnt signaling in ventral body wall development by inactivating Wls or β-catenin in murine abdominal ectoderm. The loss of Wls in the ventral epithelium, which blocks the secretion of Wnt proteins, resulted in dysgenesis of ventral musculature and genito-urinary tract during embryonic development. Molecular analyses revealed that the dermis and myogenic differentiation in the underlying mesenchymal progenitor cells was perturbed by the loss of ectodermal Wls. The activity of the Wnt-Pitx2 axis was impaired in the ventral mesenchyme of the mutant body wall, which partially accounted for the defects in ventral musculature formation. In contrast, epithelial depletion of β-catenin or Wnt5a did not resemble the body wall defects in the ectodermal Wls mutant. These findings indicate that ectodermal Wnt signaling instructs the underlying mesodermal specification and abdominal musculature formation during ventral body wall development, adding evidence to the theory that ectoderm-mesenchyme signaling is a potential unifying mechanism for the origin of ventral body wall defects.

Evaluation of Physical Function in Individuals 11 to 14 Years After Anterior Cervical Decompression and Fusion Surgery—A Comparison Between Patients and Healthy Reference Samples and Between 2 Surgical Techniques

ObjectiveThe purpose of this study was to evaluate neck-related physical function in individuals 11 to 14 years after anterior cervical decompression and fusion (ACDF) surgery for degenerative cervical disk disease and to compare the long-term outcome of 2 surgical techniques, including the Cloward procedure and cervical intervertebral fusion cage. MethodsIn this cross-sectional study, 51 individuals, 11 years or more after ACDF, underwent testing of cervical active range of motion, hand-grip strength, static and dynamic balance, neck muscle endurance, and completed pain ratings. The participants' values were compared with values of age- and sex-matched healthy individuals to evaluate impairments. Correlations between different test scores and pain were performed. Group differences were analyzed between the 2 surgical techniques. ResultsSixty-five percent and 82% exhibited impairment in ventral and dorsal neck muscle endurance, respectively. Impairment rates of 18% to 39% for cervical active range of motion, 27% to 43% for hand-grip strength, 37% for standing balance, and 35% for dynamic balance were recorded. Twenty-nine percent of the participants had impairment (>30 mm visual analog scale) in pain. There were no significant differences in physical function between the 2 surgical treatment groups (Cloward procedure or cervical intervertebral fusion cage) (P = .10-.92). ConclusionsIn those studied, a large percentage of patients who had anterior cervical decompression and fusion surgery have impairments in neck-related physical function when compared 11 to 14 years after surgery with age- and sex-matched healthy reference individuals. Neck-specific function, but not balance, was statistically correlated to pain. Neck muscle endurance was most affected, and balance impairments were also present in one-third of the individuals. There were no differences in long-term physical function between the 2 surgical techniques.

A superfast muscle in the complex sonic apparatus of Ophidion rochei (Ophidiiformes): histological and physiological approaches.

In teleosts, superfast muscles are generally associated with the swimbladder wall, whose vibrations result in sound production. In Ophidion rochei, three pairs of muscles were named 'sonic' because their contractions affect swimbladder position: the dorsal sonic muscle (DSM), the intermediate sonic muscle (ISM), and the ventral sonic muscle (VSM). These muscles were investigated thanks to electron microscopy and electromyography in order to determine their function in sound production. Fibers of the VSM and DSM were much thinner than the fibers of the ISM and epaxial musculature. However, only VSM fibers had the typical ultrastructure of superfast muscles: low proportion of myofibrils, and high proportions of sarcoplasmic reticulum and mitochondria. In females, each sound onset was preceded by the onset of electrical activity in the VSM and the DSM (ISM was not tested). The electromyograms of the VSM were very similar to the waveforms of the sounds: means for the pulse period were 3.6±0.5 and 3.6±0.7 ms, respectively. This shows that the fast VSM (ca. 280 Hz) is responsible for the pulse period and fundamental frequency of female sounds. DSM electromyograms were generally characterized by one or two main peaks followed by periods of lower electrical activity, which suggests a sustained contraction over the course of the sound. The fiber morphology of the ISM and its antagonistic position relative to the DSM are not indicative of a muscle capable of superfast contractions. Overall, this study experimentally shows the complexity of the sound production mechanism in the nocturnal fish O. rochei.

Die Bedeutung der Rumpfmuskulatur bei Eishockeyspielern: eine Machbarkeitsstudie

Good core strength is seen as a condition for high performance in sports. In general, especially maximum voluntary contraction (MVC) and strength endurance (SE) measurements of the core muscles are used. In addition, a few studies can be found that examine the core muscles in terms of MVC, rate of force development (RFD) and SE. Primary aims of this feasibility study were to investigate the feasibility regarding recruiting process, compliance and safety of the testing conditions and raise the force capabilities MVC, RFD and SE of the core muscles in amateur ice hockey players. Secondarily, tendencies of correlations between muscle activity and either shot speed and sprint time shall be examined. In this feasibility study the recruitment process has been approved by 29 ice hockey players, their adherence to the study measurements of trunk muscles, and safety of the measurements was evaluated. To determine the MVC, RFD and SE for the ventral, lateral and dorsal core muscles a dynamic force measurement was performed. To determine the correlation between core muscles and shot speed and 40-m sprint, respectively, the rank correlation coefficient (rho) from Spearman was used. The recruited number of eight field players and one goal-keeper was not very high. The compliance with 100 % was excellent. The players reported no adverse symptoms or injuries after the measurements. The results show median values for the ventral core muscles for MVC with 46.5 kg for RFD with 2.23 m/s2 and 96 s for the SE. For lateral core muscle median values of the lateral core muscles for MVC with 71.10 kg, RFD with 2.59 m/s2 and for SE over 66 s were determined. The dorsal core muscles shows values for MVC 69.7 kg, for RFD 3.39 m/s2 and for SE of 75 s. High correlations between MVC of the ventral core muscles (rho = -0.721, p = 0.021), and between the SE of the ventral core muscles (rho = 0.787, p = 0.012), and the shot velocity rate were determined. Another high correlation between SE of the ventral core muscles and sprint over 40 m (rho = 0.717, p = 0.030) could be demonstrated. This feasibility study has shown that the implementation of the selected design is adapted for future studies. Further studies are needed to better understand the relationship between the velocity rate and the MVC, and the SE respectively, as well as between the sprint and the SE.

Suspension and optical properties of the crystalline lens in the eyes of basal vertebrates

We have investigated the apparatus suspending the crystalline lens in the eyes of basal vertebrates. Data are presented for Holocephali (Chondrichthyes) and the actinopterygians Polypteriformes, Polyodontidae (Acipenseriformes), Lepisosteiformes, Amiiformes, and one teleost species, the banded archerfish (Toxotes jaculatrix). We also studied the optical properties of the lens in Polypteriformes, Lepisosteiformes, and the archerfish. Together with previously published results, our findings show that there are three basic types of lens suspension in vertebrates. These are i) a rotationally symmetric suspension (Petromyzontida, lampreys; Ceratodontiformes, lungfishes; Tetrapoda), ii) a suspension with a dorso-ventral axis of symmetry and a ventral papilla (all Chondrichthyes and Acipenseriformes), and iii) an asymmetric suspension with a ventral muscle and a varying number of ligaments (all Actinopterygii except for Acipenseriformes). Large eyes with presumably high spatial resolution have evolved in all groups. Multifocal lenses creating well-focused color images are also present in all groups studied. Stable and exact positioning of the lens, in many cases in combination with accommodative changes in lens position or shape, is achieved by all three types of lens suspension. It is somewhat surprising that lens suspensions are strikingly similar in Chondrichthyes and Acipenseriformes (Actinopterygii), while the suspension apparatus in Polypteriformes, usually being regarded as an actinopterygian group more basal than Acipenseriformes, are considerably more teleostean-like. This study completes a series of investigations on lens suspensions in nontetrapod vertebrates, covering all major groups except for the rare and highly derived coelacanths.

Endurance and fatigue characteristics in the neck muscles during sub-maximal isometric test in patients with cervical radiculopathy

The aim of the study was to compare myoelectric manifestation in neck muscle endurance and fatigue characteristics during sub-maximal isometric endurance test in patients with cervical radiculopathy and asymptomatic subjects. An additional aim was to explore associations between primary neck muscle endurance, myoelectric fatigability, and self-rated levels of fatigue, pain and subjective health measurements in patients with cervical radiculopathy. Muscle fatigue in the ventral and dorsal neck muscles was assessed in patients with cervical radiculopathy and in an asymptomatic group during an isometric neck muscle endurance test in prone and supine. 46 patients and 34 asymptomatic subjects participated. Surface electromyography signals were recorded from the sternocleidomastoid, cervical paraspinal muscles and upper and middle trapezius bilaterally during the endurance test. Subjective health measurements were assessed with questionnaires. The results showed altered neck muscle endurance in several of the muscles investigated with greater negative median frequency slope, greater variability, side imbalance, lower endurance time and higher experience of fatigue among the cervical radiculopathy patients compared with healthy subjects. Endurance times were significantly lower in both prone and in supine positions between the patients compared to asymptomatic subjects. During the neck muscle endurance test, fatigues in the upper trapezius muscles during the prone test and in the sternocleidomastoid muscles during the supine test were of more importance than self-perceived pain, fatigue, disability and kinesiophobia in predicting neck muscle endurance (NME). NME testing in the primary neck muscles seems to be an important factor to take into consideration in rehabilitation.

Organochlorine pesticides in fish from Taihu Lake, China, and associated human health risk assessment

Because contaminants and nutrients always coexist in fish, the risk from contaminants and the benefit from nutrients, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are also concomitant via fish consumption. To investigate the risk and benefit via fish consumption, concentrations of dichlorodiphenyltrichloroethane and its metabolites (DDTs), and hexachlorocyclohexanes (HCHs) in the whole- and portion-muscles of fish from Taihu Lake, China, were measured. Based on the contaminant data and nutrients from our previous study, and the associated risk and benefit via fish consumption were estimated. The concentrations of DDTs and HCHs in the whole-muscles ranged from 7.8×102 to 3.4×103pgg−1ww, and from 67.3 to 300pgg−1ww, respectively. Of DDTs and HCHs measured, p,p′-DDE and β-HCH were respectively the most abundant pesticides. The composition profiles of DDTs and HCHs suggested that the pesticides were mainly historical residues. The benefit–risk quotient (BRQ) of EPA+DHA vs. POPs (persistent organic pollutants including data of DDTs, HCHs, and those of polychlorinated biphenyls and polybrominated diphenyl ethers cited from our previous study) via consumption of fish from Taihu Lake was calculated. As a result, to achieve the recommended EPA+DHA intake of 250mgd−1 for a healthy adult, the consumption of most fish species from the lake can cause cancer and non-cancer risks. However, the fish consumption at the rates of 44.9gd−1 by Chinese would not lead to the risks for most of the species. The results also suggested that the risk of consuming silver carp was generally lower than other fish species, and those of dorsal muscles were lower than ventral and tail muscles.

Notable plesiomorphies and notable specializations: Head structure of the primitive “tongue moth” Acanthopteroctetes unifascia (lepidoptera: Acanthopteroctetidae)

The Acanthopteroctetidae are one of the first-originated family-group lineages within "tongue moths" (Lepidoptera-Glossata). The purpose of this study is to provide a comprehensive account (based on whole mount preparations, serial sections, and Scanning electron microscopy) of the cephalic structure of an adult exemplar of the family, to supplement the sparse available information. Notable plesiomorphies include the retention of frontal retractors of the narrow labrum, a high supraocular index linked to strong development of cranio-mandibular ad- and abductors, and perhaps the unusually short but still coilable (just ca. 1.5 turns) galeal "tongue." Notable specializations (probably mostly family autapomorphies) include a complement of large sensilla placodea on the male antennae, an apical attachment of the long dorsal tentorial arm to the cranium, an extreme reduction of the single-segmented labial palps, a particularly strong subgenal bridge and a surface structure of near-parallel ridges on the ommatidial corneae. The presence of sizable saccular mandibular (type 1) glands opening into the adductor apodeme is unexpected, no counterparts being known from neighboring taxa. The same is true for ventral salivarium dilator muscles originating on the prelabium; and tentatively suggested to be homologues of the extrinsic palp flexors (the insertion shift being related to loss of original function due to palp reduction), rather than to the ventral salivarium muscles of more basal insects. A complete "deutocerebral loop"' may or may not be developed, as is true for a mutual appression of the optic lobe and circumoesophageal connective/suboesophageal ganglion, enclosing the anterior tentorial arm between them; a suboesophageal innervation of the retrocerebral complex was not observed. No characters bearing on the monophyly of the Coelolepida were identified. The scapo-pedicellar articulation with a scapal process and a smooth intercalary sclerite is reminiscent of conditions in Neopseustidae, but remains debatable as a synapomorphy of the two families.

Day vs. Day-Night Use of Ankle-Foot Orthoses in Young Children with Spastic Diplegia

The aim of this study was to compare the effectiveness of treatment with hinged ankle-foot orthoses (AFOs) during the day vs. during both the day and the night in young ambulant children with spastic diplegia. In this prospective randomized controlled trial, 112 ambulatory children (70 boys and 42 girls; mean age, 2 yrs 6.93 mos; range, 1 yr 1 mo to 4 yrs 0 mo) with spastic diplegia participated. Forty-eight were classified at level I of the Gross Motor Function Classification System; the remaining 64 were at level II. Using stratified randomization, all children were assigned to either the day AFO-wearing group (n = 56, wearing AFOs all day) or the day-night AFO-wearing group (n = 56, wearing AFOs all day and all night). The two groups underwent conventional rehabilitative treatments five times a week for 8 wks. The primary outcomes measured were passive ankle dorsiflexion angle and sections D and E of the 66-item Gross Motor Function Measure; the root mean square of surface electromyography in the ventral and dorsal lower limb muscles was compared in a subgroup (ten from each group). Seven children did not complete the full intervention: three in the day AFO-wearing group and four in the day-night AFO-wearing group. Significant baseline-postintervention improvements were found for passive ankle dorsiflexion angle and the 66-item Gross Motor Function Measure in both groups (P < 0.05). On the basis of the score changes, there was no significant difference between these two groups with respect to passive ankle dorsiflexion angle; however, the improvements in the 66-item Gross Motor Function Measure were significantly better in the day AFO-wearing group (P < 0.01). A significant root mean square decrease in gastrocnemius (P < 0.05) was present after the intervention in the day AFO-wearing group, whereas the muscles affected in the day-night AFO-wearing group were the gastrocnemius (P < 0.05) and the tibialis anterior (P < 0.001). The results demonstrate that the daytime use of AFOs was more effective in improving Gross Motor Function Measure scores than the day-night use. In addition, the prolonged wearing of AFOs may influence muscle activity, which should be monitored in the clinic.

Functional and morphological variety in trunk muscles of Urodela.

ABSTRACTTrunk musculature in Urodela species varies by habitat. In this study, trunk musculature was examined in five species of adult salamanders representing three different habitats: aquatic species, Amphiuma tridactylum and Necturus maculosus; semi-aquatic species, Cynops pyrrhogaster; terrestrial species, Hynobius nigrescens and Ambystoma tigrinum. More terrestrial species have heavier dorsal and ventral trunk muscles than more aquatic forms. By contrast, the lateral hypaxial musculature was stronger in more aquatic species. The number of layers of lateral hypaxial musculature varied among Urodela species and did not clearly correlate with their habitats. The M. rectus abdominis was separated from the lateral hypaxial musculature in both terrestrial and semi-aquatic species. In aquatic species, M. rectus abdominis was not separated from lateral hypaxial musculature. Lateral hypaxial musculature differed in thickness among species and was relatively thinner in terrestrial species. In more terrestrial species, dorsal muscles may be used for stabilization and ventral flexing against gravity. Ventral muscle may be used in preventing dorsally concave curvature of the trunk by dorsal muscles and by weight. The lengthy trunk supported by limbs needs muscular forces along the ventral contour line in more terrestrial species. And, the locomotion on well-developed limbs seems to lead to a decrease of the lateral hypaxial musculature.

Rab11 Plays an Indispensable Role in the Differentiation and Development of the Indirect Flight Muscles in Drosophila

Rab11, an evolutionary conserved, ubiquitously expressed subfamily of small monomeric GTPase has been known to regulate diverse cellular and developmental events, by regulating the exocytotic and transcytotic events inside the cell. Our studies show that Rab11 regulates Drosophila adult myogenesis by controlling proliferation and differentiation of the Adult muscle precursors (AMPs). Blocking Rab11 in the AMPs, which fuse to form the Indirect Flight Muscles (IFMs) of fly, renders flies completely flightless and non-viable. The indirect flight musculature, comprising of the differentially patterned dorsal longitudinal muscles (DLMs) and dorsal ventral muscles (DVMs), is affected to different extents. Abrogating or knocking down normal Rab11 function results in severely disrupted IFMs. DLMs forming from larval templates are reduced in number along with a significant reduction in their fibre size. The de novo developing DVMs are frequently absent. The DLMs in Rab11 hypomorphs are highly reduced, showing as a small constricted mass in one half of the thorax. Further, Rab11 function is essential for growth of these muscles during later half of adult myogenesis, as down regulation of Rab11 in IFMs results in degenerated muscles and broken fibres. Finally, we show that loss of Rab11 activity in the AMPs result in acquisition of migratory characteristic of myoblast as they show cellular protrusion at their polar ends accompanied with loss of cell-cell contacts. Our data provide the first evidence of a trafficking protein playing an indispensable role in regulating early stages of adult muscle development.

Regional and segmental differences in the embryonic expression of a putative leech Hox gene, Lox2, by central neurons immunoreactive to FMRFamide-like neuropeptides

We performed immunofluorescence experiments using a rat polyclonal antibody on formaldehyde-fixed whole-mount embryos to characterize the expression of a putative leech Hox gene, Lox2, during embryonic development. The main goal was to determine whether the differentiation of subsets of FMRFamide-like immunoreactive (FLI) neurons coincide with the expression domain of Lox2. The earliest expression of Lox2 was detected in relatively large, prominent nuclei in the posterior region at embryonic day 4, a very early stage. Lox2 expression was also detected in subsets of central neurons (neurons located in the CNS) located in midbody ganglia 6 (M6)-M21. In addition, Lox2 was expressed by a number of segment-specific and segmentally repeated central FLI neurons. Lox2-positive FLI neurons of interest included some of those previously identified: the rostral most ventral (RMV) neurons, the circular ventral (CV) neurons, and cell 261. The paired RMVs, which are located in all midbody ganglia, expressed Lox2 only in M7-M19. The CV neurons, specialized motor neurons that innervate the circular ventral muscles of the body wall, expressed Lox2 in M7-M19. The putative cell 261 expressed Lox2 in M7-M12, where Lox1 is also expressed. FMRFamide staining in putative segmental homologs of cell 261 was not detected in other segmental ganglia. Our results suggest a role for Lox2 in very early embryonic development (before the formation of the CNS), and in the differentiation of segmentally repeated and region-specific FLI neurons.

Muscle Activity Influence on the Kinematics of the Cervical Spine in Frontal Tests

Objective: The question of muscle activity influence on the cervical spine kinematics during rear-end and frontal crash events has been discussed. Less data are available concerning frontal collisions. Therefore, the objective of this study was to investigate the influence of the ventral and dorsal neck muscles on the cervical spine kinematics during simulated frontal sled collisions. Methods: A frontal collision with a velocity change (delta V) of 10.2 km/h was simulated in a sled test with 10 healthy subjects (7 female; 3 male). A high-speed camera and accelerometers recorded the motion and acceleration data. The activity of the sternocleidomastoid muscles was recorded with surface electrodes. To avoid cross-talk, an intramuscular recording of the semispinalis capitis muscles was performed with fine-wire electrodes. Results: The sequence of both muscle activities was reproducible in all subjects. The maximal force of the sternocleidomastoid muscle was observed after a median of 152 ms, with 0 defining the time of the trigger signal. With earlier onset of muscle force, maximal dorsal horizontal acceleration of the head (r = −0.600) was reached later and the ventral translation (r = −0.733) and flexion movement (r = −0.755) set in earlier. The maximal force of the semispinalis capitis muscle was observed after a median of 160 ms. If the duration of muscle force was longer, the maximal head flexion (r = 0.685) and the maximal ventral head translation (r = 0.738) were reached later. Conclusions: The sternocleidomastoid muscle force is mainly associated with the horizontal head acceleration and influences the onset of the flexion and translation motion. To summarize, these temporal correlations allow the conclusion that the semispinalis capitis muscle force is mainly associated with the angular head acceleration and influences the duration of the flexion and translation motion.

Head anatomy of adult Sisyra terminalis (Insecta: Neuroptera: Sisyridae) – Functional adaptations and phylogenetic implications

The external and internal head anatomy of Sisyra terminalis is described in detail and compared with data from literature. A salivary pump consisting of a peculiar reservoir and a hitherto unknown muscle, M. ductus salivarii, is newly described for Neuroptera. The upward folded paraglossae form a secondary prolongation of the salivary system. These structures are discussed as functional adaptations for feeding on aphids and desiccated honeydew. In a phylogenetic analysis the basal position of the Sisyridae within Neuroptera is retrieved. The following new synapomorphies are postulated: (1) for Neuropterida, the presence of a M. submentomentalis and prepharyngeal ventral transverse muscles, and the absence of a M. submentopraementalis; (2) for Neuroptera and Sialidae, the presence of a mandibular gland; (3) for Neuroptera, the presence of four scapopedicellar muscles; (4) for Neuroptera exclusive Nevrorthidae and Sisyridae, the weakening of dorsal tentorial arms, the presence of a M. tentoriomandibularis medialis superior and the shifted origin of M. tentoriocardinalis.

MAGNETIC RESONANCE IMAGING CONTRAST ENHANCEMENT OF EXTRA‐OCULAR MUSCLES IN DOGS WITH NO CLINICAL EVIDENCE OF ORBITAL DISEASE

Enhancement of extra-ocular muscles has been reported in cases of orbital pathology in both veterinary and medical magnetic resonance imaging. We have also observed this finding in the absence of orbital disease. The purpose of this retrospective study was to describe extra-ocular muscle contrast enhancement characteristics in a group of dogs with no known orbital disease. Magnetic resonance images (MRI) from dogs with no clinical evidence of orbital disease and a reportedly normal MRI study were retrieved and reviewed. Contrast enhancement percentages of the medial, lateral, ventral, and dorsal rectus muscles were calculated based on signal-to-noise ratios that were in turn determined from hand-traced regions of interest in precontrast, immediate postcontrast and 10-min postcontrast scans. Comparison measurements were made in the pterygoid muscle. Contrast enhancement of the extra-ocular muscles was observed in all patients (median contrast enhancement percentage 45.0%) and was greater than that of pterygoid muscle (median contrast enhancement percentage 22.7%). Enhancement of the extra-ocular muscles persisted 10 min after contrast administration (median contrast enhancement percentage 43.4%). Findings indicated that MRI contrast enhancement of extra-ocular muscles is likely normal in dogs.

Suture anchor placement technique around the insertion of the ventral rectus muscle for the replacement of the prolapsed gland of the third eyelid in dogs: 100 dogs

To evaluate a rapid and efficacious procedure to anchor the prolapsed gland of the third eyelid in dogs. This is a retrospective study of 100 affected dogs (122 eyes) with third eyelid gland prolapse that were surgically anchored with a nonabsorbable suture around the insertion of the ventral rectus muscle. Hundred dogs (122 eyes) were included in this study. Twenty-three pure-bred and several mixed-breed dogs were represented with the right eye affected in 60 cases and the left eye in 62 cases. Thirty-four eyes (27.9%) were previously operated on at another facility prior to referral. The average age of the patients was 2.2 years (57 days to 11 years). No recurrences of gland prolapse were observed over the course of study. Minor intraoperative conjunctival perforations were observed and easily repaired at the time of the surgery in 21 cases (17.2%). Five cases demonstrated preexistent keratoconjunctivitis sicca (KCS), and all had improved Schirmer tear test following surgical correction and medical therapy. The suture anchor placement technique provides a cosmetic, rapid, and successful replacement of the prolapsed gland of the third eyelid in dogs. No recurrences were noted. Complications were easily addressed.

Morphofunctional analysis of Svobodaina species (Brachiopoda, Heterorthidae) from south‐western Europe

AbstractGeometric morphometric methods applied to the ventral muscle field outline of the various species of Svobodaina from south‐western Europe identify criteria for discriminating among this key cluster of brachiopod species. These data indicate the close relationship between the patterns of the ventral muscle field in the Svobodaina species and the environmental conditions where each inhabited; the fields are better developed in species related to high‐energy environments. For example, S. armoricana, with the smallest diductor scars, would have inhabited the quiet marine environments of the lower offshore or within protected lagoonal settings. S. feisti would have inhabited the upper offshore, a more energetic environment than S. armoricana. Finally, S. havliceki, with the largest diductor scars, would have thrived in the most energetic environments among all the south‐western European Svobodaina species, living just above the fair‐weather wave base in the lower shoreface. The palaeoecological results suggest a distribution of Svobodaina species during the Late Ordovician along an onshore–offshore transect across the shallow marine platforms of the Mediterranean margin of Gondwana. On the other hand, the occurrence in some localities of several species with overlapping ranges or within the same assemblage indicates that the biostratigraphical efficacy of the genus is restricted. Thus, the previously defined taxon‐range biozones characterized by Svobodaina species of the north Gondwanan margin are in need of reassessment. The morphology of Svobodaina may be a considerable aid to environmental analyses rather than to precise biostratigraphical correlations.

Initiation of primary myogenesis in amniote limb muscles

Vertebrate muscles are defined and patterned at the stage of primary myotube formation, but there is no clear description of how these cells form in vivo. Of particular interest is whether primary myotubes are "seeded" by a unique myoblast population that differentiates as mononucleated myocytes, similar to the founder myoblasts of insects. We analyzed the cell populations and processes leading to initiation of primary myogenesis in limb buds of rats and mice. Pax3(+ve) myogenic precursors migrate into the limb bud and initially consolidate into dorsal and ventral muscle masses in the absence of Pax7 expression. Approximately a day later, Pax7(+ve) cells appear in the central aspect of the limb base and subsequently throughout the limb muscle masses. Primary myogenesis is initiated within each muscle mass at a time when only Pax3, and not Pax7, protein can be detected. Primary myotubes form initially as elongate mononucleated myocytes, well before cleavage of the muscle masses has occurred. Multinucleate myotubes appear approximately a day later. A similar process is seen during initiation of chick limb primary myogenesis. Primary myotubes of vertebrate limb muscles are initiated by mononucleated myocytes, that appear structurally analogous to the founder myoblasts of insects.

The ultrastructure of the striated muscles of Derocheilocaris typica (Mystacocarida, Crustacea)

The striated muscles of Derocheilocaris typica consist of mononucleated cells, each containing one filament bundle. Large muscles consist of two or more cells adjacent to each other. The mitochondria line up along the filament bundle on one side. The nucleus is situated in the mitochondrial row and has a small cytoplasmic area around it filled with glycogen. The sarcomeres are between 3 and 6 μm long. The Z-line and H band are present. Six thin filaments surround one thick filament. All muscles belong to the phasic type. The tubular system emanates from the ends of the muscle cell and penetrates the whole cell. The tubules are formed as cisterns, which also open at the cell membrane at the level of the I bands. They have sarcoplasmic cisterns on both sides forming a continuous triad system. Partially transformed epidermal cells mediate muscle insertions on the cuticle. Tendons are formed with the transformed epidermal cells being supplemented by fibroblasts forming collagen fibers. Dorsal and ventral abdominal muscles are innervated from the dorso-lateral nerve arising from the nerve chain. Each muscle cell receives one axon, which forms one synapse on the mitochondrial-free side of the muscles. Axons form terminal spines, which make axo-axonal synapses.