Biomaterial Database

The corneal stroma: an inhomogeneous structure. 1997

S Langefeld, and M Reim, and C Redbrake, and N F Schrage

Universitätsaugenklinik der RWTH Aachen, Germany.

OBJECTIVE This study was conducted to determine the elemental composition of the human cornea. Special attention was paid to corneal stroma inhomogeneity. METHODS Seventy human corneas were examined by means of energy-dispersive X-ray analysis. Epithelium, subepithelium, middle stroma, sub-Descemet layer, Descemet's membrane and endothelium were subjected to repeated measurements. RESULTS In the cellular layers the phosphorus concentrations were high [0.35 mol/kg dry weight (dw) in the epithelium and 0.403 mol/kg dw in the endothelium]. Similar concentrations were found for sulphur (0.38 mol/kg dw in the epithelium). Stromal layers showed high contents of sulphur: 0.26 mol/kg dw. The phosphorus concentration was found to be higher in the subepithelium than in the middle stroma. Sulphur concentrations were highest in Descemet's membrane, followed by the subepithelium and the middle stroma. CONCLUSIONS Nucleic acids and energy-containing phosphates explain the high levels of phosphorus in the cellular layers. The high sulphur concentrations may be related to the phosphoadenosinphosphosulfate and protein turnover in the epithelium. We interpret the inhomogeneous distribution of phosphorus in the stroma as a function of the density of keratocytes. An evaluation of all known sulphur-containing biochemical components of the stroma (0.217 mol sulphur/kg dw) corresponds to our measurements. In contrast to former results we find the corneal stroma to be an inhomogeneous structure.

UI	MeSH Term	Description	Entries
D010758	Phosphorus	A non-metal element that has the atomic symbol P, atomic number 15, and atomic weight 31. It is an essential element that takes part in a broad variety of biochemical reactions.	Black Phosphorus,Phosphorus-31,Red Phosphorus,White Phosphorus,Yellow Phosphorus,Phosphorus 31,Phosphorus, Black,Phosphorus, Red,Phosphorus, White,Phosphorus, Yellow
D012016	Reference Values	The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.	Normal Range,Normal Values,Reference Ranges,Normal Ranges,Normal Value,Range, Normal,Range, Reference,Ranges, Normal,Ranges, Reference,Reference Range,Reference Value,Value, Normal,Value, Reference,Values, Normal,Values, Reference
D003319	Corneal Stroma	The lamellated connective tissue constituting the thickest layer of the cornea between the Bowman and Descemet membranes.	Corneal Stromas,Stroma, Corneal,Stromas, Corneal
D003886	Descemet Membrane	A layer of the cornea. It is the basal lamina of the CORNEAL ENDOTHELIUM (from which it is secreted) separating it from the CORNEAL STROMA. It is a homogeneous structure composed of fine collagenous filaments, and slowly increases in thickness with age.	Lamina Elastica Posterior,Descemet's Membrane,Descemet Membranes,Descemets Membrane,Elastica Posterior, Lamina,Elastica Posteriors, Lamina,Lamina Elastica Posteriors,Membrane, Descemet,Membrane, Descemet's,Membranes, Descemet,Posterior, Lamina Elastica,Posteriors, Lamina Elastica
D004577	Electron Probe Microanalysis	Identification and measurement of ELEMENTS and their location based on the fact that X-RAYS emitted by an element excited by an electron beam have a wavelength characteristic of that element and an intensity related to its concentration. It is performed with an electron microscope fitted with an x-ray spectrometer, in scanning or transmission mode.	Microscopy, Electron, X-Ray Microanalysis,Spectrometry, X-Ray Emission, Electron Microscopic,Spectrometry, X-Ray Emission, Electron Probe,X-Ray Emission Spectrometry, Electron Microscopic,X-Ray Emission Spectrometry, Electron Probe,X-Ray Microanalysis, Electron Microscopic,X-Ray Microanalysis, Electron Probe,Microanalysis, Electron Probe,Spectrometry, X Ray Emission, Electron Microscopic,Spectrometry, X Ray Emission, Electron Probe,X Ray Emission Spectrometry, Electron Microscopic,X Ray Emission Spectrometry, Electron Probe,X-Ray Microanalysis,Electron Probe Microanalyses,Microanalyses, Electron Probe,Microanalysis, X-Ray,Probe Microanalyses, Electron,Probe Microanalysis, Electron,X Ray Microanalysis,X Ray Microanalysis, Electron Microscopic,X Ray Microanalysis, Electron Probe
D004728	Endothelium, Corneal	Single layer of large flattened cells covering the surface of the cornea.	Anterior Chamber Epithelium,Corneal Endothelium,Endothelium, Anterior Chamber,Epithelium, Anterior Chamber,Anterior Chamber Endothelium
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000368	Aged	A person 65 years of age or older. For a person older than 79 years, AGED, 80 AND OVER is available.	Elderly
D013455	Sulfur	An element that is a member of the chalcogen family. It has an atomic symbol S, atomic number 16, and atomic weight [32.059; 32.076]. It is found in the amino acids cysteine and methionine.	Sulfur-16,Sulfur 16