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Structural and Ultrastructural Analysis of the Cervical Discs of Young and Elderly Humans.

Fontes RB, Baptista JS, Rabbani SR, Traynelis VC, Liberti EA - PLoS ONE (2015)

Bottom Line: Macroscopic degenerative features such as loss of annulus-nucleus distinction and fissures were found in both groups and significantly more severe in G2 as expected.Collagen detection was significantly decreased in G2: although significant intradiscal differences were rare, changes may occur faster or earlier in the posterior annulus.These results demonstrate an extensive modification of the ECM with maintenance of basic ultrastructural features despite severe macroscopic degeneration.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, SP, Brazil; Department of Neurosurgery, Rush University Medical Center, Chicago, IL, United States of America.

ABSTRACT
Several studies describing the ultrastructure and extracellular matrix (ECM) of intervertebral discs (IVDs) involve animal models and specimens obtained from symptomatic individuals during surgery for degenerative disease or scoliosis, which may not necessarily correlate to changes secondary to normal aging in humans. These changes may also be segment-specific based on different load patterns throughout life. Our objective was to describe the ECM and collagen profile of cervical IVDs in young (G1 - <35 years) and elderly (G2 - >65 years) presumably-asymptomatic individuals. Thirty cervical discs per group were obtained during autopsies of presumably-asymptomatic individuals. IVDs were analyzed with MRI, a morphological grading scale, light microscopy, scanning electron microscopy (SEM) and immunohistochemistry (IHC) for collagen types I, II, III, IV, V, VI, IX and X. Macroscopic degenerative features such as loss of annulus-nucleus distinction and fissures were found in both groups and significantly more severe in G2 as expected. MRI could not detect all morphological changes when compared even with simple morphological inspection. The loose fibrocartilaginous G1 matrix was replaced by a denser ECM in G2 with predominantly cartilaginous characteristics, chondrocyte clusters and absent elastic fibers. SEM demonstrated persistence of an identifiable nucleus and Sharpey-type insertion of cervical annulus fibers even in highly-degenerated G2 specimens. All collagen types were detected in every disc sector except for collagen X, with the largest area stained by collagens II and IV. Collagen detection was significantly decreased in G2: although significant intradiscal differences were rare, changes may occur faster or earlier in the posterior annulus. These results demonstrate an extensive modification of the ECM with maintenance of basic ultrastructural features despite severe macroscopic degeneration. Collagen analysis supports there is not a "pathologic" collagen type and changes are generally similar throughout the disc. Understanding the collagen and ultrastructural substrate of degenerative changes in the human disc is an essential step in planning restorative therapies.

No MeSH data available.


Related in: MedlinePlus

Light microscopy slides.A well-delimited structure of fibrous lamellae in both anterior and posterior AF of G1 discs is substituted for a degenerated phenotype in G2 with compact, fibrocartilaginous matrix populated with numerous chondrocyte clusters. Sharpey-type insertion of AF fibers (arrows) into the endplate (asterisks) is well visualized in G1 discs and maintained in G2. In the anterior AF, fibers insert directly into the endplate while in the posterior sector this insertion is at an obtuse angle (arrows). Elastic fibers were rarely found in G2 discs, regardless of Thompson (Th) score. SR, Sirius Red. HE, hematoxylin and eosin.
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pone.0139283.g003: Light microscopy slides.A well-delimited structure of fibrous lamellae in both anterior and posterior AF of G1 discs is substituted for a degenerated phenotype in G2 with compact, fibrocartilaginous matrix populated with numerous chondrocyte clusters. Sharpey-type insertion of AF fibers (arrows) into the endplate (asterisks) is well visualized in G1 discs and maintained in G2. In the anterior AF, fibers insert directly into the endplate while in the posterior sector this insertion is at an obtuse angle (arrows). Elastic fibers were rarely found in G2 discs, regardless of Thompson (Th) score. SR, Sirius Red. HE, hematoxylin and eosin.

Mentions: A morphologically “young” fibrocartilaginous phenotype consisted of an anterior AF (aAF) with dense alternating lamellae, predominantly longitudinal in more superficial areas and oblique in deeper sectors, and a thinner posterior AF (pAF) with predominantly longitudinal fibers (Fig 3). Even in G1, a central area of discernible loose connective tissue was seen in only 2/30 cervical discs; the usual finding was a central area of denser fibrous tissue with chondrocyte clusters in its interior. Under polarized light, the AF lamellae can be seen to firmly insert themselves into the adjacent endplates in the manner of Sharpey’s fibers—regardless of how degenerated the disc was, the central area never exhibited these insertions. Elastic fibers were found aligned with the connective tissue lamellae in the AF and staining was concordant between the Verhoeff and Weigert techniques, suggesting these fibers are of the mature elastic type. Elastic fibers were found in smaller quantities in more degenerated G1 specimens but were still present.


Structural and Ultrastructural Analysis of the Cervical Discs of Young and Elderly Humans.

Fontes RB, Baptista JS, Rabbani SR, Traynelis VC, Liberti EA - PLoS ONE (2015)

Light microscopy slides.A well-delimited structure of fibrous lamellae in both anterior and posterior AF of G1 discs is substituted for a degenerated phenotype in G2 with compact, fibrocartilaginous matrix populated with numerous chondrocyte clusters. Sharpey-type insertion of AF fibers (arrows) into the endplate (asterisks) is well visualized in G1 discs and maintained in G2. In the anterior AF, fibers insert directly into the endplate while in the posterior sector this insertion is at an obtuse angle (arrows). Elastic fibers were rarely found in G2 discs, regardless of Thompson (Th) score. SR, Sirius Red. HE, hematoxylin and eosin.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4591259&req=5

pone.0139283.g003: Light microscopy slides.A well-delimited structure of fibrous lamellae in both anterior and posterior AF of G1 discs is substituted for a degenerated phenotype in G2 with compact, fibrocartilaginous matrix populated with numerous chondrocyte clusters. Sharpey-type insertion of AF fibers (arrows) into the endplate (asterisks) is well visualized in G1 discs and maintained in G2. In the anterior AF, fibers insert directly into the endplate while in the posterior sector this insertion is at an obtuse angle (arrows). Elastic fibers were rarely found in G2 discs, regardless of Thompson (Th) score. SR, Sirius Red. HE, hematoxylin and eosin.
Mentions: A morphologically “young” fibrocartilaginous phenotype consisted of an anterior AF (aAF) with dense alternating lamellae, predominantly longitudinal in more superficial areas and oblique in deeper sectors, and a thinner posterior AF (pAF) with predominantly longitudinal fibers (Fig 3). Even in G1, a central area of discernible loose connective tissue was seen in only 2/30 cervical discs; the usual finding was a central area of denser fibrous tissue with chondrocyte clusters in its interior. Under polarized light, the AF lamellae can be seen to firmly insert themselves into the adjacent endplates in the manner of Sharpey’s fibers—regardless of how degenerated the disc was, the central area never exhibited these insertions. Elastic fibers were found aligned with the connective tissue lamellae in the AF and staining was concordant between the Verhoeff and Weigert techniques, suggesting these fibers are of the mature elastic type. Elastic fibers were found in smaller quantities in more degenerated G1 specimens but were still present.

Bottom Line: Macroscopic degenerative features such as loss of annulus-nucleus distinction and fissures were found in both groups and significantly more severe in G2 as expected.Collagen detection was significantly decreased in G2: although significant intradiscal differences were rare, changes may occur faster or earlier in the posterior annulus.These results demonstrate an extensive modification of the ECM with maintenance of basic ultrastructural features despite severe macroscopic degeneration.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, SP, Brazil; Department of Neurosurgery, Rush University Medical Center, Chicago, IL, United States of America.

ABSTRACT
Several studies describing the ultrastructure and extracellular matrix (ECM) of intervertebral discs (IVDs) involve animal models and specimens obtained from symptomatic individuals during surgery for degenerative disease or scoliosis, which may not necessarily correlate to changes secondary to normal aging in humans. These changes may also be segment-specific based on different load patterns throughout life. Our objective was to describe the ECM and collagen profile of cervical IVDs in young (G1 - <35 years) and elderly (G2 - >65 years) presumably-asymptomatic individuals. Thirty cervical discs per group were obtained during autopsies of presumably-asymptomatic individuals. IVDs were analyzed with MRI, a morphological grading scale, light microscopy, scanning electron microscopy (SEM) and immunohistochemistry (IHC) for collagen types I, II, III, IV, V, VI, IX and X. Macroscopic degenerative features such as loss of annulus-nucleus distinction and fissures were found in both groups and significantly more severe in G2 as expected. MRI could not detect all morphological changes when compared even with simple morphological inspection. The loose fibrocartilaginous G1 matrix was replaced by a denser ECM in G2 with predominantly cartilaginous characteristics, chondrocyte clusters and absent elastic fibers. SEM demonstrated persistence of an identifiable nucleus and Sharpey-type insertion of cervical annulus fibers even in highly-degenerated G2 specimens. All collagen types were detected in every disc sector except for collagen X, with the largest area stained by collagens II and IV. Collagen detection was significantly decreased in G2: although significant intradiscal differences were rare, changes may occur faster or earlier in the posterior annulus. These results demonstrate an extensive modification of the ECM with maintenance of basic ultrastructural features despite severe macroscopic degeneration. Collagen analysis supports there is not a "pathologic" collagen type and changes are generally similar throughout the disc. Understanding the collagen and ultrastructural substrate of degenerative changes in the human disc is an essential step in planning restorative therapies.

No MeSH data available.


Related in: MedlinePlus