Longitudinal Fibers Research Articles

Thermomechanical and dynamic mechanical properties of bamboo/woven kenaf mat reinforced epoxy hybrid composites

The dimensional stability and dynamic mechanical properties on bamboo (non woven mat)/kenaf (woven mat) hybrid composites was carried out in this study. The hybridization effect of bamboo (B) and kenaf (K) fibers at different weight ratio were studied at B:K:70:30, and B:K:30:70 while maintaining total fiber loading of 40% by weight. The coefficient of thermal expansion (CTE) and dynamic mechanical properties of composites were analyzed by thermomechanical anlayzer (TMA), and dynamic mechanical analyzer (DMA), respectively. Positive hybridization effects were observed on B:K:50:50 hybrid composite with lowest CTE and highest dynamic mechanical properties among all composites. The dimensional stability were strongly influence by the fiber orientation where all composites shows prominent expansion in the transverse fibers direction but relatively low expansion in longitudinal fibers direction. Dynamic mechanical properties in term of complex modulus (E*), storage modulus (E′), loss modulus (E″), Tan delta and Cole-Cole plot were studied. DMA results reveal that B:K:50:50 hybrid composite possess the highest complex modulus due to the strong fiber/matrix interfacial bonding which supported by the coefficient of effectiveness and Cole-Cole plot. Hence, it is concluded that 50:50 weight ratio of bamboo and kenaf fibers is the optimum mixing ratio to enhance both dimensional and dynamic mechanical properties of hybrid composites, and it can be utilized for automotive or building materials applications which demand high dimensional stability and dynamic mechanical properties.

Standardized phytotherapic extracts rescue anomalous locomotion and electrophysiological responses of TDP-43 Drosophila melanogaster model of ALS

Findings from studies using animal models expressing amyotrophic lateral sclerosis (ALS) mutations in RNA-binding proteins, such as Transactive Response DNA-binding protein-43 (TDP-43), indicate that this protein, which is involved in multiple functions, including transcriptional regulation and pre-mRNA splicing, represents a key candidate in ALS development. This study focuses on characterizing, in a Drosophila genetic model of ALS (TDP-43), the effects of Mucuna pruriens (Mpe) and Withania somnifera (Wse). Electrophysiological and behavioural data in TDP-43 mutant flies revealed anomalous locomotion (i.e. impaired climbing with unexpected hyperactivity) and sleep dysregulation. These features, in agreement with previous findings with a different ALS model, were at least partially, rescued by treatment with Mpe and Wse. In addition, electrophysiological recordings from dorsal longitudinal muscle fibers and behavioral observations of TDP-43 flies exposed to the volatile anaesthetics, diethyl ether or chloroform, showed paradoxical responses, which were normalized upon Mpe or Wse treatment. Hence, given the involvement of some potassium channels in the effects of anaesthetics, our results also hint toward a possible dysregulation of some potassium channels in the ALS-TDP-43 Drosophila model, that might shed new light on future therapeutic strategies pertaining to ALS.

Comparative histological studies of Jejunum in cattle, sheep and goat

Jejunum in cattle, sheep and goat comprised four types of layers tunica mucosa, tunica submucosa, tunica muscularis and tunica serosa. Tunica mucosa was innermost layer, which comprised lamina propria with number of glands. Intestinal glands were lined by number of goblet cells tall columnar cells and enterochromaffin cells. Lamina muscularis was with circular and longitudinal layers of smooth muscle fibre. Tunica muscularis was comprised of circular and longitudinal muscle fiber. Outrmost layer was tunica serosa which was a loose connective tissue with blood vessels.

Compressive mechanical properties and failure modes of Zr-based bulk metallic glass composites containing tungsten springs

A novel kind of Zr-based bulk metallic glass composites (BMGCs) reinforced with tailored volume fractions of tungsten springs were designed. The effect of tungsten springs on the compressive mechanical properties and failure modes of the BMGCs was investigated. As increasing the volume fraction of tungsten springs, the yield strength decreases slightly, however, both the fracture strength and plastic strain increase significantly. The continuity and special geometry shape of the tungsten springs are revealed to account for the enhanced fracture strength and plasticity. The BMGCs with lower volume fractions of tungsten springs exhibit a unique cone-shaped fracture morphology due to the preferential initiation of shear bands in the central metallic glass matrix. While the BMGCs with larger volume fractions of tungsten springs exhibit a mixed shear fracture morphology consisting of four distinct regions. Nevertheless, all the current BMGCs fail in a shear mode, which is obviously different from that of the BMGCs reinforced with longitudinal fibers. The failure modes of the BMGCs can be modified by designing the structure and orientation of the tungsten springs.

Morphological framework for attachment and locomotion in several Digenea of the families Microphallidae and Heterophyidae.

Digenea usually use ventral sucker for sustainable attachment within intestine of their definitive vertebrate host. However, if the ventral sucker is absent or poorly developed, the means of attachment are unclear. We investigated attachment and locomotion in such digeneans: three species of the family Microphallidae (Microphallus piriformes, M. pygmaeus, and Levinseniella brachysoma) and two species of the family Heterophyidae (Cryptocotyle concava and C. lingua). Their tegumental spines and musculature were described with use of fluorescent actin staining, confocal microscopy, and scanning electron microscopy. Locomotion of living worms was observed and recorded. Wide serrated tegumental spines probably play the main role in attachment. Their firm contact with the host mucosa may be provided by the action of the ventral concavity-when the entire body or its part acts as a sucker. Dorsoventral muscle bundles act like radial musculature of the sucker generating negative pressure in the ventral concavity. The solid layer of longitudinal muscle fibers on the ventral body surface provides support for the bottom of the ventral concavity. In all microphallids, a U-shaped arrangement of body wall musculature (mostly originating from longitudinal fibers) outlines posterior part of the ventral concavity ridge. In all the studied species, tegumental spines, body wall musculature, and dorsoventral muscle bundles are better developed in the forebody which moves more actively than the hindbody.

Experimental study on shear-dominant fiber failure in CFRP laminates by out-of-plane shear loading

Understanding the shear behavior and resulting fiber failure of fiber-reinforced plastics is required for better prediction of their behavior during the machining process, but knowledge regarding the shear strength of fiber failure is limited. In this study, out-of-plane shear tests were conducted to observe the shear behavior of carbon fiber-reinforced plastic laminates subjected to high shear stress exceeding the shear strength of matrix failure. The longitudinal fibers in carbon fiber-reinforced plastic unidirectional laminates were cut by shear loading without severe internal damage and the maximum shear stress causing progressive fiber breaks was much higher than the shear strength of matrix failure. This result suggested the possibility of out-of-plane shearing as a machining method for fiber-reinforced plastics and shear tests were subsequently performed for carbon fiber-reinforced plastic cross-ply laminates. Delamination was generated by high shear stress to cut the reinforcing fibers, but the size of the remaining damage was small even in the thermoset carbon fiber-reinforced plastic laminates in which delamination likely occurs, without any optimization of the trimming conditions.

Influence of fiber orientation and weld position in welding injection-molded fiber-reinforced thermoplastics

Several publications deal with the influence of the initial fiber orientation in joining parts on the weld strength of fiber-reinforced thermoplastics. The welding partners have been sawn before welding. Preparing the joining parts after injection molding is not suitable since it is an additional manufacturing step. Since injection molding results in a non-uniform fiber orientation, there is a possibility that the position of the weld influences weld characteristics. The influence of the initial fiber orientation was investigated by preparing parts with longitudinal or transverse initial fiber orientation. Short and long glass fiber-reinforced thermoplastics with a glass fiber content of 30% have been welded by hot-plate and vibration welding. The initial fiber orientation in non-welded parts influences the weld strength: longitudinal fibers are more advantageous for the weld strength than transverse fibers. The influence of the position of the weld in injection-molded parts was investigated by welding the plates at the end of the flow path, at the sawn gate, and at the lateral side. The weld strength is similar at the gate or at the end of the flow path. For PA-GF30, the weld strength at the gate is even higher. Positioning the weld at the lateral side in injection-molded parts results in significantly lower weld strengths for short and long glass fiber-reinforced thermoplastics in hot-plate and vibration welding.

Damage mechanisms under static and fatigue loading at locally compacted regions in a high pressure resin transfer molded carbon fiber non-crimp fabric

Manufacturing defects are an issue of composite manufacturing processes. Local clamping is proposed to prevent fiber washout during high pressure resin transfer molding of non-crimp fabrics. At the clamping regions the material is compacted by through-the-thickness compression. The current work investigates the mechanical performance of such regions under static and fatigue loading. Two typical manufacturing defects are intrinsic to the compacted regions: fiber undulation and resin starved/dry spots. In component tests the thereby generated damage is monitored using 3D digital image correlation and the complete processes of damage initiation and propagation are analyzed. Static and low cycle fatigue failure are dominated by fiber undulation at the edges of the compacted region, triggering matrix damage and delaminations. High cycle fatigue is dominated by decreasing fiber matrix adhesion within the compacted region, leading to longitudinal splitting and progressive fiber failure. Identification of damage initiation is supported by numerical finite element simulations.

The DH31/CGRP enteroendocrine peptide triggers intestinal contractions favoring the elimination of opportunistic bacteria.

The digestive tract is the first organ affected by the ingestion of foodborne bacteria. While commensal bacteria become resident, opportunistic or virulent bacteria are eliminated from the gut by the local innate immune system. Here we characterize a new mechanism of defense, independent of the immune system, in Drosophila melanogaster. We observed strong contractions of longitudinal visceral muscle fibers for the first 2 hours following bacterial ingestion. We showed that these visceral muscle contractions are induced by immune reactive oxygen species (ROS) that accumulate in the lumen and depend on the ROS-sensing TRPA1 receptor. We then demonstrate that both ROS and TRPA1 are required in a subset of anterior enteroendocrine cells for the release of the DH31 neuropeptide which activates its receptor in the neighboring visceral muscles. The resulting contractions of the visceral muscles favors quick expulsion of the bacteria, limiting their presence in the gut. Our results unveil a precocious mechanism of defense against ingested opportunistic bacteria, whether they are Gram-positive like Bacillus thuringiensis or Gram-negative like Erwinia carotovora carotovora. Finally, we found that the human homolog of DH31, CGRP, has a conserved function in Drosophila.

Subpicosecond pulse generation above 2 μm in longitudinally inhomogeneous single-mode fibres

We consider the evolution of the spectrum of a medium-power input telecom laser pulse during propagation in a longitudinally inhomogeneous flattened dispersion silica fibre. Using modelling results, we find an optimal longitudinal fibre diameter profile ensuring transfer of more than 60 % of the input pulse energy to a subpicosecond pulse in the range 2.2 – 2.3 μm.

Development of white matter fibre density and morphology over childhood: A longitudinal fixel-based analysis

PurposeWhite matter fibre development in childhood involves dynamic changes to microstructural organisation driven by increasing axon diameter, density, and myelination. However, there is a lack of longitudinal studies that have quantified advanced diffusion metrics to identify regions of accelerated fibre maturation, particularly across the early pubertal period. We applied a novel longitudinal fixel-based analysis (FBA) framework, in order to estimate microscopic and macroscopic white matter changes over time. MethodsDiffusion-weighted imaging (DWI) data were acquired for 59 typically developing children (27 female) aged 9–13 years at two time-points approximately 16 months apart (time-point 1: 10.4 ± 0.4 years, time-point 2: 11.7 ± 0.5 years). Whole brain FBA was performed using the connectivity-based fixel enhancement method, to assess longitudinal changes in fibre microscopic density and macroscopic morphological measures, and how these changes are related to sex, pubertal stage, and pubertal progression. Follow-up analyses were performed in sub-regions of the corpus callosum to confirm the main findings using a Bayesian repeated measures approach. ResultsThere was a statistically significant increase in fibre density over time localised to medial and posterior commissural and association fibres, including the forceps major and bilateral superior longitudinal fasciculus. Increases in fibre cross-section were substantially more widespread. The rate of fibre development was not associated with age or sex. In addition, there was no significant relationship between pubertal stage or progression and longitudinal fibre development over time. Follow-up Bayesian analyses were performed to confirm the findings, which supported the null effect of the longitudinal pubertal comparison. ConclusionUsing a novel longitudinal fixel-based analysis framework, we demonstrate that white matter fibre density and fibre cross-section increased within a 16-month scan rescan period in specific regions. The observed increases might reflect increasing axonal diameter or axon count. Pubertal stage or progression did not influence the rate of fibre development in the early stages of puberty. Future work should focus on quantifying these measures across a wider age range to capture the full spectrum of fibre development across the pubertal period.

Morphology of the Stomach of Tayra (Eira barbara)

Background: The Tayra (Eira barbara) is a mammal of the family Mustelidae with a significant presence in Latin America, it is considered an opportunist and extremely agile omnivorous. Some organs compose the digestive system and the stomach is a substantial organ for this system. The stomach have a small and a large curvature and the regions of the cardia, fundus, body and pylorus. Histologically, the stomach is made up of four layers or tunics that contributes in digestive functions. However, due the limited information available in the literature about morphophysiology of wildlife, this study aimed to clarify the morphology of Eira barbara stomach to understand your digestive system.Materials, Methods & Results: Three males and three females of Eira barbara species were studied (all young adults), all samples were originated of the Bauxite Mine area, in Paragominas, Pará state, Brazil provided of donation to Morphological Animal Research Laboratory (LaPMa) of the Universidade Federal Rural da Amazonia (UFRA), after death by trampling. The corpses were treated with aqueous 10% formaldehyde solution intramuscular injections, subcutaneous and intracavitary. After dissection, the collected material was processed following histologic standard protocols for the subsequent preparation of slides. The studied animals showed the stomach on the left antimere the abdominal cavity, with saccular format with the presence of large and small curvatures. The organ showed composite mucosa made with various gastric folds distributed in regions of the cardia, fundus and pylorus. A microscopic analysis of Eira barbara stomach revealed the presence of tunics or layers which gradually invaginate the lumen of the organ and underlying lamina propria was located to the prismatic epithelium and muscular mucosae and mucosa itself. In the region of the cardia, the muscle layer was deeply situated on the lamina propria, consisting of smooth muscle tissue with circular and longitudinal fibers. The submucosa consists of loose connective tissue; it is much thicker than the lamina propria and has many vessels. The first portion of the stomach showed long glands, while with short pits. In light microscopy, the fundic region revealed the presence of a highly pleated epithelium with elongated glands composed of clear and basally placed cells, with flattened nuclei. These cells are named mucous. Along the short region of the gastric pits, the presence of large cells was reported, pyramidal or rounded, central nucleus, called parietal. The pyloric region microscopy revealed the presence of short glands, similar to those previously described in the cardia region. The wide presence of goblet cells in the final portion of the pylorus indicated gradual transition between the regions of the stomach to the intestine, called duodenum-pylorus transition. The muscular layer showed thick muscle bundles just in circular direction, being responsible for the formation of the pyloric sphincter.Discussion: The morphological analysis of the stomachs showed morphological and topographical similarities to the literature description for pets and wild mammals, however, were found in abundant quantities goblet cells in the transition duodenal pylorus. The goblet cells are located throughout the length of the small and large intestine and are responsible for the production and maintenance of the protective mucus synthesizing as glycoproteins known as mucins.

Exploratory study of adopting longitudinal column reinforcement details as a design-controllable tool to seismic behavior of exterior RC beam-column joints

This study presents the test results of seven exterior beam-column joints with different longitudinal reinforcement details for the columns. The test program included a beam-column joint designed to serve as a control specimen, in which column reinforcement was continuous ribbed steel bars. The other six specimens were divided into two groups, three specimens for each group. In the first group, the longitudinal column reinforcement was detailed with well-confined lap-splice longitudinal bars: two specimens were reinforced with lap-splice deformed steel bars and the later was with lap-splice plain steel bars. The same reinforcement details were used for the second group but additional longitudinal basalt fiber reinforced polymer (BFRP) rebars were placed at the joint and extended to the upper and lower columns. The test results showed that splicing the longitudinal column reinforcement successfully reduced the contribution of the joint to the deformability of the beam-column joint. Furthermore, adding BFRP rebars to the beam-column joint could be applied as damage controllable bars reducing both the damage level at the serviceability state and the shear deformability of the joint up to failure. A sole strut resistant mechanism was realized by the joints of all test specimens detailed with lap-spliced longitudinal column reinforcement. Ultimately, the test results point to a probability to the renunciation of the ACI 318-11 requirements for splicing longitudinal column reinforcement at column mid-height.

TECHNOLOGY VELOCITY VECTOR IMAGING AND STANDARD ECHOCARDIOGRAPHI TO ASSESS LEFT VENTRICLE IN PATIENTS WITH NON Q MIOCARDIAL INFARCTION

The purpose of the study was to assess the function of fibres of the left ventricle (LV) and its dynamics after revascularization in patients with non Q myocardial infarction using standard Echocardiography (EchoCG) and Velocity Vector Imaging (VVI). Materials and methods: 34 patients with MI were examined. Echocardiography studies were performed on the ultrasound scanner AcusonX 300 (Siemens), a 1–5 MHz transducer before and in early period after coronary artery bypass grafting (CABG). Results. Standard EchoCG showed systolic LV dysfunction before and after CABG, contractile dysfunction in 51 (8%) segment before the operation, with subsequent recovery of the function of the 28 (54%) of them. The effect of MI on LV function using VVI showed reducing strain (S) and normal strain rate (SR) of the longitudinal fibers, decrease S and SR of circular fibers and normal function of radial fibers. After GABG S and SR of longitudinal fibers has not changed, S and SR of the circular fibres are decreased. The function of radial fibers are normal. The study established a relationship between the level of LDH-1 and SR of the circular fibers of the LV prior to CABG. Increased level of LDH-1 in the early period after CABG can be a predictor of reduction of S and SR circular fibers. Conclusion: In patients with it is necessary to analyze not only the longitudinal and radial fibers, but also circular.

Seismic collapse assessment of bridge piers constructed with steel fibers reinforced concrete.

Steel fiber is one of the most widely used reinforcements to improve the performance of concrete members. However, few studies have been proposed to study the seismic performance of bridge piers constructed with steel fiber reinforced concrete. This paper presents the collapse vulnerability assessment of typical single bridge piers constructed with steel fibers. Fiber element models of RC bridge piers with and without steel fibers are firstly built by selecting suitable cyclic constitutive laws of steel fiber reinforced concrete, and then calibrated using the experimental results. The seismic capacity and inelastic demand of RC piers with steel fibers are quantified using both nonlinear static pushover analyses and nonlinear incremental dynamic analyses (IDA). In order to conduct the IDA, a suite of 20 earthquake ground motions are selected and scaled to different levels of peak ground acceleration (PGA). Collapse fragility curves are then generated using the maximum drift ratio of piers as the engineering demand parameter (EDP). In order to investigate the impact of various parameters on the collapse fragility curves, six parameters are considered in the parametric study: peak compressive strength of concrete, yield strength of steel, longitudinal reinforcement ratio, axial load ratio, transverse hoops ratio and steel fiber content. It was observed that the concrete strength, longitudinal reinforcement ratio and steel fiber content could significantly affect the collapse fragility curve of the bridge piers with steel fibers.

Morphology of the bryozoan Cinctipora elegans (Cyclostomata, Cinctiporidae) with first data on its sexual reproduction and the cyclostome neuro-muscular system

BackgroundCyclostome bryozoans are an ancient group of marine colonial suspension-feeders comprising approximately 700 extant species. Previous morphological studies are mainly restricted to skeletal characters whereas data on soft tissues obtained by state-of-the-art methods are still lacking. In order to contribute to issues related to cyclostome ground pattern reconstruction, we analyzed the morphology of the neuromuscular system Cinctipora elegans by means of immunocytochemical staining, confocal laser scanning microscopy, histological sections and microCT imaging.ResultsPolypides of C. elegans are located in elongated tubular skeletal cystids. Distally, the orifice leads into a prominent vestibulum which is lined by an epithelium that joins an almost complete perimetrical attachment organ, both containing radially arranged neurite bundles and muscles. Centrally, the prominent atrial sphincter separates the vestibulum from the atrium. The latter is enclosed by the tentacle sheath which contains few longitudinal muscle fibers and two principal neurite bundles. These emerge from the cerebral ganglion, which is located at the lophophoral base. Lateral ganglia are located next to the cerebral ganglion from which the visceral neurite bundles emerge that extend proximally towards the foregut. There are four tentacle neurite bundles that emerge from the ganglia and the circum-oral nerve ring, which encompasses the pharynx. The tentacles possess two striated longitudinal muscles. Short buccal dilatators are situated at the lophophoral base and short muscular sets are present at the abfrontal and frontal side of the tentacle base. The pharynx is myoepithelial and triradiate in cross-section. Oocytes are found inside the pharyngeal myoepithelium. The digestive tract contains dense circular musculature and few longitudinal muscles. The membranous sac contains regular, thin, circular and diagonal muscles and neurites in its epithelial lining.ConclusionsThe general structure of the neuro-muscular system is more reminiscent of the condition found in Gymnolaemata rather than Phylactolaemata, which supports a close relationship between Cyclostomata and Gymnolaemata. Several characters of C. elegans such as the lateral ganglia or loss of the cardia are probably apomorphic for this species. For the first time, oocytes that surprisingly develop in the pharyngeal wall are reported for this species.

Increasing flexural performance of hybrid sandwich panels by using strain hardening cementitious base composite and glass fiber-reinforced polymer

The present paper explores different techniques for increasing flexural performance of composite sandwich panels made of hand-layup glass fiber reinforced polymer skins and low density closed cell polyurethane foam core. An experimental program compares the performance of simple panels face to the use of transversal and longitudinal internal glass fiber reinforced polymer ribs and the installation of a strain hardening cementitious base composite top layer over the panels. Based on the experimental results, finite element models are also developed to simulate the flexural behavior of tested panels and conducted an in depth analysis of the techniques studied. Obtained experimental and numerical results show that the use of internal glass fiber reinforced polymer ribs (especially in longitudinal direction) along with the use of strain hardening cementitious base composite significantly and effectively increases the flexural performance of sandwich panels. The high stiffness to weight ratio capacity of the panels attained by applying the proposed method enables its use in rehabilitation of historical places. Furthermore, the proposed techniques could be helpful for strengthening available composite sandwich panels.

Otopathologic evaluation of temporalis fascia grafts following successful tympanoplasty in humans.

Temporalis fascia is a commonly used graft material in tympanoplasty; however, little is known about how the histological structure of fascia remodels postimplantation. Herein, we aim to quantify the pre- and postoperative microstructure of temporalis fascia and compare histological findings to the native tympanic membrane (TM). Temporal bone specimens having undergone successful subtotal or total drum replacement using temporalis fascia were identified (n = 3). Surgically prepared preimplantation temporalis fascia (PreTF, n = 4) and normal TMs (n = 5) were used as controls. Multiple measurements of thickness of PreTF and of normal and fascia reconstructed TMs at the mesotympanum and hypotympanum were obtained. Collagen fiber patterns of normal and reconstructed TMs were histologically described. In cases of fascia tympanoplasty, the mean time of surgery to death was 16 years (range 8-28 years). All cases contained an aerated middle ear without residual perforation. There was no significant difference between the thickness of PreTF and fascia of reconstructed TMs (234.9 ± 144.9 μm vs. 162.9 ± 71.9 μm, P = 0.1). The lamina propria and total thicknesses of controls (59.8 ± 39.3 μm and 83.7 ± 42.4 μm, respectively) were thinner than the PreTF and fascia-reconstructed TMs, respectively, in all cases (P ≤ 0.001, P ≤ 0.001). Reconstructed TMs contained a thick, longitudinal fiber structure that was qualitatively similar to PreTF. Based on human temporal bone specimens, temporalis fascia does not significantly remodel, change thickness, or change fibrous structure following successful tympanoplasty. Results have implications for selection and surgical preparation of graft materials in TM reconstruction. 4. Laryngoscope, 128:E351-E358, 2018.

Elongation Rule of the Longitudinal Fiber of the Continuous Roll Forming Part

Continuous roll forming is a novel technique for low-cost, high-efficient manufacturing of three-dimensional surface part. Comparing with conventional continuous forming (using at least three rolls), continuous roll forming employs an upper and a lower flexible rolls to shape the sheet metal. The desired forming shape can be obtained by controlling the profile of the flexible roll and the gap between upper and lower flexible rolls. Modeling and simulation of the continuous roll forming process based on finite element analyses is established to investigate the elongation rule of the longitudinal fiber of the continuous roll forming part. The length of the longitudinal fiber at different positions across the thickness direction is discussed, and the mechanism of the longitudinal deformation is clarified. The following conclusions are obtained. When the flexible roll profile and the roll gap distribution meet certain conditions and make length of the longitudinal fiber linearly distributed, the longitudinal deformation of the sheet metal can be generated.

Fluid outflow in the rat spinal cord: the role of perivascular and paravascular pathways

BackgroundCerebrospinal fluid (CSF) is thought to flow into the brain via perivascular spaces around arteries, where it mixes with interstitial fluid. The precise details concerning fluid outflow remain controversial. Although fluid dynamics have been studied in the brain, little is known about spinal cord fluid inflow and outflow. Understanding the normal fluid physiology of the spinal cord may give insight into the pathogenesis of spinal cord oedema and CSF disorders such as syringomyelia. We therefore aimed to determine the fluid outflow pathways in the rat spinal cord.MethodsA fluorescent tracer, Alexa-Fluor®-647 Ovalbumin, was injected into the extracellular space of either the cervicothoracic lateral white matter or the grey matter in twenty-two Sprague–Dawley rats over 250 s. The rats were sacrificed at 20 or 60 min post injection. Spinal cord segments were sectioned and labelled with vascular antibodies for immunohistochemistry.ResultsFluorescent tracer was distributed over two to three spinal levels adjacent to the injection site. In grey matter injections, tracer spread radially into the white matter. In white matter injections, tracer was confined to and redistributed along the longitudinal axonal fibres. Tracer was conducted towards the pial and ependymal surfaces along vascular structures. There was accumulation of tracer around the adventitia of the intramedullary arteries, veins and capillaries, as well as the extramedullary vessels. A distinct layer of tracer was deposited in the internal basement membrane of the tunica media of arteries. In half the grey matter injections, tracer was detected in the central canal.ConclusionsThese results suggest that in the spinal cord interstitial fluid movement is modulated by tissue diffusivity of grey and white matter. The central canal, and the compartments around or within blood vessels appear to be dominant pathways for fluid drainage in these experiments. There may be regional variations in fluid outflow capacity due to vascular and other anatomical differences between the grey and white matter.