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G. Graff; Phospholipid Fatty Acid Composition of the Corneal Epithelium and Stroma of the Rabbit and Human Cadaver Tissue . Invest. Ophthalmol. Vis. Sci. 2004;45(13):3815.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:Assess and compare the fatty acid composition of membrane phospholipids of the corneal epithelium and stroma of the NZA rabbit with that of human cadaver tissue. Methods: Corneas were dissected, placed on an ice–cold glass surface and corneal buttons (0.71cm2) were prepared with a trephine. The epithelium and stroma was isolated and extracted with a mixture of CHCl3/CH3OH as described by Bligh and Dyer1. Lipids were separated by TLC. The phospholipid fraction was isolated and trans–esterified (4% H2SO4 in methanol). The fatty acid methyl esters formed were extracted and quantified by gas liquid chromatography with the aid of appropriate internal standards. Results: Membrane phospholipids of the corneal epithelium of the rabbit exhibited a simple fatty acid composition with palmitate (C16:0; 38.2 mole%), stearate (C18:0 = 19.8 mol%) and oleate (C18:1; 42.0 mol%) being the only phospholipid fatty acyl chains. This was in contrast to the stroma which exhibited notable quantities of both C18:2 (7.1 mole%) and C20:4 (3.2 mol %), in addition to the saturated and monoenoic acids found in the epithelium. A similar fatty acyl chain pattern to the rabbit was evident in phospholipids of the stroma of human cadaver tissue, with C18:2 and C20:4 reaching levels up to 2.4 mol% and 4.3 mol%, respectively. C18:0 was the major saturated fatty acyl chain of phospholipids of both the epithelium and stroma. The most striking difference between the rabbit and human cornea was apparent in the phospholipid C18:2 and C20:4 fatty acyl chain abundance of the epithelium. While rabbit corneal epithelium was devoid of C18:2 and C20:4, phospholipids of the human corneal epithelium showed considerable variability in C18:2 and C20:4 abundance, ranging from non–detectable to as high as 18.2 mole%. Conclusion:The fatty acid profile of phospholipids of the corneal stroma of the NZA rabbit is similar to that of human cadaver tissue with minor differences in relative abundance. The corneal epithelium of the rabbit, however, appears to be distinct from that of the human by the absence of both C18:2 and C20:4. Both acids were detected in human tissue. However, their abundance was highly variable presumably due to nutritional influences.
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