Human intervertebral disc: Structure and function

Humzah, M. D.; Soames, Roger

doi:10.1002/ar.1092200402

Cited by 494 publications

(374 citation statements)

References 103 publications

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“…Better connectivity was observed at the IVD-VEP and IVD-CEP junctions than between the CEP and VEP where, at the IVD-CEP interface in particular, good fibre integration was seen, concurring with previous findings at these interfaces [17], [13], [12], [27]. Due to the presence of the epiphyseal ring in human spines, there are fibres from the outer AF continuing into the VEP, whilst those at the inner AF continue into the CEP.…”

Section: Discussionsupporting

confidence: 88%

“…Failure at the interface between the IVD and VEP appears to be a main contributor in the aetiology of herniations [33], [25], [38], with endplate being present in almost 50% of herniated disc tissue [20], but structural integrity at this junction has not previously been investigated in the aetiology of disc degeneration Several studies report clear integration between the IVD and CEP, with collagen fibres running seamlessly between the two tissues [17], [13], [12], [27]; a recent study by Herrero et al [11] focussed on non-degenerate human spines and showed that integration at the CEP-VEP junction changes with age and with spinal level. It is well recognised that, at the outer annulus fibrosus (AF), fibres are continuous from the IVD to the VEP [14], but integration at the CEP-VEP interface remains questionable, with some proposing that it is present [12] and others that it is not [27], [13].…”

Section: Introductionmentioning

confidence: 99%

“…It is well recognised that, at the outer annulus fibrosus (AF), fibres are continuous from the IVD to the VEP [14], but integration at the CEP-VEP interface remains questionable, with some proposing that it is present [12] and others that it is not [27], [13].…”

Section: Introductionmentioning

confidence: 99%

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Staying connected: structural integration at the intervertebral disc–vertebra interface of human lumbar spines

et al. 2016

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Purpose:To investigate the microscopic fibrous integration between the intervertebral disc, cartilage endplates and vertebral endplates in human lumbar spines of varying degrees of degeneration using differential interference contrast (DIC) optics. Weakness at these junctions is considered to be an important factor in the aetiology of disc herniations. Methods:Magnetic resonance images (MRIs) of cadaveric lumbar spines were graded for degeneration and motion segments from a range of degenerative grades isolated and bisected sagittally. Following fixation and decalcification, these were cut into segments containing anterior or posterior annulus fibrosus or nucleus pulposus. The segments were cryo-sectioned and sections visualised using both standard light and DIC microscopy. Results:Detachment at the interface between the disc and vertebrae increased with greater degenerative grade (from 1.9% in Grade I to 28% in Grade V), especially at the boundary between the cartilage and vertebral endplates. DIC microscopy revealed the fibrous organisation at the IVD-cartilage endplate interface with structural features, such as annular lamellae branching and nodal insertions in the nucleus pulposus region; these have been previously observed in ovine spines, but were less uniform in humans.Structural integrity of the IVD and cartilage endplate was also lost with increasing degeneration. Conclusions:This preliminary study shows that microscopic structural features may act to maintain attachment between the IVD and CEP in the human spine. Loss of structural integrity in this region may destabilise the spine, possibly altering the mechanical environment of the cells in the disc and so potentially contribute to the aetiopathogenesis of IVD degeneration.

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Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

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Staying connected: structural integration at the intervertebral disc–vertebra interface of human lumbar spines

et al. 2016

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“…Chemical fixation in this extended state followed by decalcification then enabled us to show microscopically and ultrastructurally the existence of discrete nodal insertions into the cartilaginous endplate and confirmed the existence of actual structural integration between the nucleus and endplate. These findings contrast with the more widely held view that the inner nucleus is a largely unstructured gelatinous substance which possesses little or no structural cohesion with its surroundings [3][4][5].…”

Section: Introductioncontrasting

confidence: 91%

Influence of maturity on nucleus–endplate integration in the ovine lumbar spine

2014

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Purpose Recent investigations using an ovine spine model have established that the disc nucleus contains a highly convoluted fibre network with endplate-to-endplate connectivity, this connectivity being achieved via distinctive nodal attachment points. The purpose of this study was to investigate how this nodal anchoring system might be influenced by maturation. Methods Lumbar motion segments were dissected from newborn, 3, 12 months and fully mature ovine animals, subjected to a novel annular ring-severing procedure to remove the strain-limiting influence of the annulus, then either mechanically tested to destruction or examined microstructurally and ultrastructurally. The morphology of the nodes and their linear density within the relatively thin section planes were analysed to provide a basis for comparison between the four age groups. Results Mechanical testing following ring severing revealed that the remaining nuclear material in all samples, irrespective of maturity, had the ability to transmit a substantial load from endplate to endplate. Imaging of the ring-severed samples from all age groups in their stretched, but unruptured state revealed the presence of axially aligned fibrosity in the nucleus region consistent with endplate-to-endplate connectivity. Endplate insertion nodes were observed in all age groups. Ultrastructural examination revealed that the fibrillar architecture of these nodes in the newborn discs was similar to that observed in the nodes of mature discs. However, there was a rapid increase in their linear density between birth and 3 months, after which this remained constant. Conclusions The nodal attachment points identified previously in mature ovine discs are also present in newborn, and 3-and 12-month-old animals with an initial rapid increase in their linear density between birth and 3 months, after which it remained constant. The size and morphology of the attachment points were similar for all ages. Our study suggests that the increase in nodal density in the ovine disc endplate is part of an adaptive response to the loading environment that the disc is exposed to from birth to maturity.

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“…It is composed of several connective tissues of dissimilar composition and structure and it is the dynamic interplay between these in the biocomposite IVD which equips it with its unique biomechanical properties and ability to act as a viscoelastic and hydrodynamic weight bearing cushion absorbing and dissipating axial spinal compressive loads [5,7,16,22,40,49,50]. The outermost region of the IVD, the annulus fibrosus (AF) is composed of collagenous lamellae which convey tensile properties and along with the superior and inferior hyaline-like cartilaginous endplates, prevent the inner proteoglycan rich region of the IVD, the nucleus pulposus (NP) being extruded anteriorly or posteriorly during axial and torsional spinal loading.…”

Section: Introductionmentioning

confidence: 99%

Aggrecan, versican and type VI collagen are components of annular translamellar crossbridges in the intervertebral disc

et al. 2007

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The aim of this study was to undertake a detailed analysis of the structure of the inter and intralamellar regions of the annulus fibrosus. A total of 30 newborn to 6 year-old lumbar ovine intervertebral discs (IVDs) were fixed and decalcified en-bloc to avoid differential swelling artifacts during processing and vertical midsagittal, and horizontal 4 lm sections were cut. These were stained with toluidine blue to visualise anionic proteoglycan (PG) species, H & E for cellular morphology and picrosirius red (viewed under polarized light) to examine collagenous organization. Immunolocalisations were also undertaken using anti-PG core-protein and glycosaminoglycan (GAG) side chain antibodies to native chondroitin sulphate (CS), D C-4-S and C-6-S unsaturated stubs generated by chondroitinase ABC digestion of CS, keratan sulphate (KS), and with antibodies to type I, II, VI, IX and X collagens. Trans-lamellar cross bridges (TLCBs), discontinuities in annular lamellae's which provide transverse interconnections, stained prominently with toluidine blue in the adult IVDs but less so in the newborn IVDs. In adult discs TLCBs were evident in both the posterior and anterior AF where they extended from the outermost annular lamellae almost to the transitional zone extending across as many as eight lamellar layers displaying a characteristic circuitous, meandering, serpentine type course. There were significantly fewer TLCBs in 2 week-old compared with skeletally mature sheep and there was a further increase from 2 to 6 years. Immunolocalisation of perlecan delineated blood vessels in the TLBs of the newborn but not adult IVDs extending into the mid AF. In contrast adult but not 2 week-old TLCBs were immunpositive for C-4-S, C-6-S, KS, aggrecan, versican and type VI collagen. The change in number and matrix components of the translamellar cross bridges with skeletal maturity and ageing suggest that they represent an adaptation to the complex biomechanical forces occurring in the annulus fibrosus.

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Human intervertebral disc: Structure and function

Cited by 494 publications

References 103 publications

Staying connected: structural integration at the intervertebral disc–vertebra interface of human lumbar spines

Staying connected: structural integration at the intervertebral disc–vertebra interface of human lumbar spines

Influence of maturity on nucleus–endplate integration in the ovine lumbar spine

Aggrecan, versican and type VI collagen are components of annular translamellar crossbridges in the intervertebral disc

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