Abstract: The present invention provides an agent and a method for enhancing a contrast of an image of fluorescent staining of a lumen of the digestive tract with an intravenously administered fluorescent dye, wherein the agent for enhancing a contrast is an agent for a lumen of the digestive tract containing an aqueous solution having a buffer capacity and having a pH of 6 to 10.

Abstract: A histofluorescent stain for endoscopy having good fluorescent stainability for the inner part of tissues is provided. A histofluorescent stain composition for endoscopy, containing a compound represented by the following Formula (1) wherein R1 and R2, which may be identical or different, each represent an alkyl group having 1 to 5 carbon atoms; and X? represents an anion residue.

Abstract: A fluorescent stain which has a function of clarifying the shape of the surface of the gastrointestinal lumen in the visible light wavelength region, and simultaneously, emitting fluorescence by being excited by light of a specific wavelength, and which is also biologically safe and is suitable for endoscopic observation, is provided. A histofluorescent stain composition for endoscopy, containing a compound represented by the following Formula (1): wherein R1 represents a hydrogen atom or a hydroxyl group; R3 represents a phenyl group or methyl group, to which R2c is bound; one to three of R2a, R2b and R2c represent —SO3M (wherein M represents an alkali metal atom or an alkaline earth metal atom), or —SO3NH4, and when one represents —SO3?, the others represent hydrogen atoms is provided.

Abstract: It is intended to provide means for more clearly showing an image of fluorescent staining of a lumen of the digestive tract. The present invention provides an agent for enhancing a contrast of an image of fluorescent staining of a lumen of the digestive tract with an intravenously administered fluorescent dye, wherein the agent for enhancing a contrast is an agent for a lumen of the digestive tract containing an aqueous solution having a buffer capacity and having a pH of 6 to 10.

Abstract: It is intended to provide a method for fluorescently staining a tissue accurately and clearly by convenient procedures and a staining agent used in this method. The present invention provides a method for fluorescently staining a tissue, comprising treating a tissue with a solution comprising fluorescein or a salt thereof and then fluorescently observing the treated portion under an acidic condition of lower than pH 7.

Abstract: The invention relates to a histostain composition for endoscope containing one or more members selected from colors derived from Monascus. The stain composition is a staining agent which sharpens the shapes of digestive tract lumen surfaces and the like with a light in the visible wavelength range, having a function of being excited by a light of specific wavelength to emit fluorescence, and being biologically safe and suitable for endoscopy.