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Questions and Answers
What percentage of the corneal thickness is comprised of the stratified surface epithelium?
What percentage of the corneal thickness is comprised of the stratified surface epithelium?
What is the function of the microvilli on the surface cells of the corneal epithelium?
What is the function of the microvilli on the surface cells of the corneal epithelium?
What is the function of the basement membrane in the corneal epithelium?
What is the function of the basement membrane in the corneal epithelium?
What is the composition of the stroma in the cornea?
What is the composition of the stroma in the cornea?
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What is the function of the proteoglycans in the ground substance of the stroma?
What is the function of the proteoglycans in the ground substance of the stroma?
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What is the function of the keratocytes in the stroma?
What is the function of the keratocytes in the stroma?
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Study Notes
Corneal Epithelium
- Comprises about 10% of the corneal thickness
- Consists of 5 or 6 cell layers
- Basal cells have a high proliferative capacity for renewal and repair of the corneal surface
- Stem cells in the corneoscleral limbus give rise to basal cells
- Flattened surface cells have microvilli protruding into a protective tear film of lipid, glycoprotein, and water
- Has one of the richest sensory nerve supplies of any tissue
Basement Membrane (Bowman's Membrane)
- Very thick (8-10 μm)
- Contributes to the stability and strength of the cornea
- Helps protect against infection of the underlying stroma
Corneal Stroma (Substantia Propria)
- Makes up 90% of the cornea's thickness
- Consists of approximately 60 layers of parallel collagen bundles
- Collagen bundles aligned at approximately right angles to each other
- Collagen fibrils extend almost the full diameter of the cornea
- Uniform orthogonal array of collagen fibrils contributes to the transparency of the avascular tissue
Keratocytes and Ground Substance
- Keratocytes are flattened fibroblast-like cells
- Cytoplasmic extensions of keratocytes are found between the collagen lamellae
- Ground substance around keratocytes contains proteoglycans such as lumican, with keratan sulfate and chondroitin sulfate
- Proteoglycans help maintain the precise organization and spacing of the collagen fibrils
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Description
Learn about the structure and function of the corneal epithelium and basement membrane, including their composition, cell layers, and nerve supply.
