Stroma of cornea

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Stroma of cornea
substantia propria
  • Lamellae, the fibers of which are cut across, producing a dotted appearance
  • Corneal corpuscles appearing fusiform in section
  • Lamellae, the fibers of which are cut longitudinally
  • Transition to the sclera, with more distinct fibrillation, and surmounted by a thicker epithelium
  • Small blood vessels cut across near the margin of the cornea
    • Details
    Identifiers
    Latinsubstantia propria corneae
    MeSHD003319
    TA98A15.2.02.020
    FMA58306
    Anatomical terminology]

    The stroma of the cornea (or substantia propria) is a fibrous, tough, unyielding, perfectly transparent and the thickest layer of the cornea of the eye. It is between Bowman's layer anteriorly, and Descemet's membrane posteriorly.

    At its centre, a human corneal stroma is composed of about 200 flattened

    keratocytes
    (corneal connective tissue cells), which occupy about 10% of the substantia propria.

    Apart from the cells, the major non-aqueous constituents of the stroma are collagen fibrils and

    Donnan effect. The increased water volume between the fibrils results in forces that tend to push the fibrils apart. A balance between attractive and repulsive forces is reached for specific inter-fibrillar distances, which depends on the type of proteoglycans present.[3]
    Locally, the separations between adjacent collagen fibrils are very uniform.

    Stromal transparency is mainly a consequence of the remarkable degree of order in the arrangement of the collagen fibrils in the lamellae and of fibril diameter uniformity. Light entering the cornea is scattered by each fibril. The arrangement and the diameter of the fibrils is such that scattered light interferes constructively only in the forward direction, allowing the light through to the retina.[4]

    The fibrils in the lamellae are directly continuous with those of the sclera, in which they are grouped together in fibre bundles. More collagen fibres run in a temporal-nasal direction than run in the superior-inferior direction.

    During development of the embryo, the corneal stroma is derived from the

    mesenchymal stem cells.[6]

    Disorders of stroma

    References

    1. OL 8562710W
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    2. PMID 11070369
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    3. PMID 20159468
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    4. PMID 26145225
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    5. PMID 7084153
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    6. PMID 22736610
      .

    External links
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