Observations on the ultrastructure of equatorial scleral collagen fibrils in sheep eyes

Doughty, Michael J.

doi:10.1111/j.1463-5224.2011.00938.x

Cited by 7 publications

(11 citation statements)

References 25 publications

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“…The corneoscleral shell structure has been studied extensively using atomic force14, transmission15 and scanning electron microscopies16, polarized light5, bright field10 and nonlinear microscopies17, as well as small-angle light scattering18 and small and wide-angle x-ray scattering19202122. Although these ex vivo imaging techniques have provided fundamental information on the microarchitecture and biochemistry of the tissue microstructures and collagen across ocular tissues with excellent resolution and sensitivity7, most of these techniques require chemical tissue processing or tissue sectioning, which is highly invasive and can be destructive or affect the true morphology of the collagen (e.g.…”

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confidence: 99%

Non-invasive MRI Assessments of Tissue Microstructures and Macromolecules in the Eye upon Biomechanical or Biochemical Modulation

Sigal

Jan

et al. 2016

Sci Rep

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The microstructural organization and composition of the corneoscleral shell (CSS) determine the biomechanical behavior of the eye, and are important in diseases such as glaucoma and myopia. However, limited techniques can assess these properties globally, non-invasively and quantitatively. In this study, we hypothesized that multi-modal magnetic resonance imaging (MRI) can reveal the effects of biomechanical or biochemical modulation on CSS. Upon intraocular pressure (IOP) elevation, CSS appeared hyperintense in both freshly prepared ovine eyes and living rat eyes using T2-weighted MRI. Quantitatively, transverse relaxation time (T2) of CSS increased non-linearly with IOP at 0–40 mmHg and remained longer than unloaded tissues after being unpressurized. IOP loading also increased fractional anisotropy of CSS in diffusion tensor MRI without apparent change in magnetization transfer MRI, suggestive of straightening of microstructural fibers without modification of macromolecular contents. Lastly, treatments with increasing glyceraldehyde (mimicking crosslinking conditions) and chondroitinase-ABC concentrations (mimicking glycosaminoglycan depletion) decreased diffusivities and increased magnetization transfer in cornea, whereas glyceraldehyde also increased magnetization transfer in sclera. In summary, we demonstrated the changing profiles of MRI contrast mechanisms resulting from biomechanical or biochemical modulation of the eye non-invasively. Multi-modal MRI may help evaluate the pathophysiological mechanisms in CSS and the efficacy of corneoscleral treatments.

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confidence: 99%

Non-invasive MRI Assessments of Tissue Microstructures and Macromolecules in the Eye upon Biomechanical or Biochemical Modulation

Sigal

Jan

et al. 2016

Sci Rep

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“…Scleral tissue was composed of compacted bundless of collagen fibers. These fibers tended to be rounder in outer regions of sheep eyes compared to inner regions [22] . In most of the animals the outer layer of sclera or episclera also consists of loss connective tissues that are very vascular and contain neural fibers [15] .…”

Section: Histologic Discussionmentioning

confidence: 99%

Tek Hörgüçlü Devede Gözün Fibröz Tabakasında Histoanatomik Çalışmalar

Saadatlou¹

2017

Kafkas Univ Vet Fak Derg

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Citation of This ArticleKarabag K, Alkan S, Mendes M: Histoanatomical studies on the fibrous tunic of eye in dromedary camel. Kafkas Univ Vet Fak Derg, 23 (6): 911-915, 2017. DOI: 10.9775/kvfd.2017 AbstractThis study was conducted to understand the macroscopic and microscopic structures of the fibrous tunic of 20 healthy adult dromedary camel eyes. First, the fibrous tunic of the eye was anatomically examined in terms of appearance, dimensions, location and structure. Then prepared histological slides were studied microscopically after staining by H&E, Verhoeff, Trichrome masson's and P.A.S. The result showed that in the oval-shaped camel cornea, the internal angle is rounder than the external one. The average cornea length (lateral-medial), width (dorsal-ventral), and thickness were respectively measured as 2.91±0.05, 2.07±0.04, and 0.12±0.05 cm. The thickest part of sclera is in the posterior pole of the eyeball. There was not any Bowman's membrane in camels. Descemet's membrane includes a rather even, pink, thick and shapeless membrane. Descemet's membrane is characterized with a very high positive P.A.S. reaction. Caudal endothelium of cornea did not show positive P.A.S. reaction and is observed in the form of a thin band attached to descemet's membrane. In the structure of sclera, the collagen fibers are remarkably thick, and the longitudinal and transverse cross sections are observed in the form of alternating layers. There were small elastic fibers in camel sclera. In anatomy, except for some differences, the cornea and sclera of the camel are similar to those of the other ungulates. Except for a little differences in Bowman's layer and descemet's membrane, it is similar to the fibrous tunic of the other animals. Keywords: Dromedary camel, Eye, Fibrous tunic, Histoanatomy Tek Hörgüçlü Devede Gözün Fibröz Tabakasında Histoanatomik Çalışmalar ÖzetBu çalışma tek hörgüçlü 20 adet sağlıklı erişkin devede gözün fibröz tabakasının makroskobik ve mikroskobik yapılarını araştırmak amacıyla yapılmıştır. İlk olarak gözün fibröz tabakası anatomik olarak görünüş, boyut, yerleşim ve yapı bakımından incelendi. Sonrasında, hazırlanan histolojik kesitler H&E, Verhoeff, Masson'un üçlü boyası ve PAS ile boyanarak mikroskopik olarak araştırıldı. Oval şekilli deve korneasında iç açının dış açıdan daha yuvarlak olduğu gözlemlendi. Ortalama kornea uzunluğu (lateral-medial), genişliği (dorsal-ventral) ve kalınlığı sırasıyla 2.91±0.05, 2.07±0.04 ve 0.12±0.05 cm olarak ölçüldü. Skleranın en kalın yeri göz yuvarlağının posterior kutbuydu. Develerde Bowman membranı bulunmamaktaydı. Descement membranı daha düz, pembe, kalın ve şekilsiz membrandan oluşmaktaydı. Descement membranı çok fazla PAS pozitif reaksiyon ile karakterize idi. Korneanın kaudal endoteliumu PAS pozitif reaksiyon göstermezken, descement membrana bağlı ince bir bant şeklinde gözlemlendi. Skleranın yapısında kollajen fibriller oldukça kalın olup longitudinal ve transversal kesitlerde yer değiştiren formlarda gözlemlendi. Deve sklerasında küçük elastik fibriller bulu...

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“…The material for the present studies was from recent post‐mortem sheep eyes obtained from a local slaughterhouse by special arrangements . The eyes were earlier washed in cold tap water and, over a five‐year period, small batches of eyes (usually 10 to 15) in closed containers were received at the laboratory within two hours post‐mortem.…”

Section: Methodsmentioning

confidence: 99%

“…A few drops of freshly‐prepared fixative solution were applied to the ocular surface every few minutes over a period of 90 minutes. The fixative was at room temperature and composed of 2 per cent glutaraldehyde in 80 mmol/l sodium cacodylate buffer, pH 7.2 to 7.4, 320 to 340 mOsm/kg . The anterior chamber fluid was then exchanged for fixative using a syringe and further drops of fixative applied to the surface over five to 10 minutes.…”

Section: Methodsmentioning

confidence: 99%

Assessment of size and nucleo‐cytoplasmic characteristics of the squamous cells of the corneal epithelium

Doughty

2015

Clinical and Experimental Optometry

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Purpose:The aim was to objectively assess size, nucleus and nucleo-cytoplasmic ratio features of squamous cells from the corneal epithelium Methods: The corneas of recent post-mortem sheep eyes were either glutaraldehyde-fixed for transmission electron microscopy or impression cytology samples taken, glutaraldehydefixed and stained with Giemsa. From the specimens for impression cytology, a representative region was photographed from 12 different samples taken from the central region and 16 different samples taken from mid-peripheral regions of the corneal epithelium. Images were subjected to morphometry after overlays were generated. Results: Electron microscopy revealed a very distinctive stratified corneal epithelium with several superficial layers, confirming the squamous phenotype. Impression cytology from such superficial layers revealed a cell size of 60.1 ± 4.8 μm, nucleus dimension of 12.3 ± 1.5 μm, cell area of 2,419 ± 416 μm 2 and nucleus area of 131 ± 31 μm 2 . A nucleo-cytoplasmic ratio based on nucleus-to-cell length had a mean of 0.207 ± 0.022, while a cytoplasm-tonucleus length ratio was 3.975 ± 0.474. Estimates of the nucleo-cytoplasmic ratio based on areas had a mean value of 0.059 ± 0.011. Very similar results were found for mid-peripheral corneal epithelium. Conclusions:The results strongly indicate that the squamous phenotype of the superficial corneal epithelial cells is characterised by a large size, large nucleus and low nucleocytoplasmic ratio. These morphological characteristics show a notable resemblance to data obtained from impression cytological studies on human conjunctival epithelial cells showing severe squamous metaplasia.

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Observations on the ultrastructure of equatorial scleral collagen fibrils in sheep eyes

Abstract: The equatorial sclera is a mixture of rounder versus flatter collagen fiber bundles, the former being more likely to be made up of a mixture of both smaller and larger fibrils, as compared to slightly smaller fibrils.

Cited by 7 publications

References 25 publications

Non-invasive MRI Assessments of Tissue Microstructures and Macromolecules in the Eye upon Biomechanical or Biochemical Modulation

Non-invasive MRI Assessments of Tissue Microstructures and Macromolecules in the Eye upon Biomechanical or Biochemical Modulation

Tek Hörgüçlü Devede Gözün Fibröz Tabakasında Histoanatomik Çalışmalar

Assessment of size and nucleo‐cytoplasmic characteristics of the squamous cells of the corneal epithelium

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