[ENDOCYTOSCOPY--NOVEL ENDOSCOPIC DIAGNOSTICS APPROACH: PRINCIPLES AND PROCEDURE].

Abstract Endocytoscopy is one of the most novel endoscopic diagnostic procedures, providing optical magnification up to 1150 times of gastrointestinal and respiratory tract mucosa. Such approach allows real-time tissue and cellular structure visualization. Endocytoscopy, along with confocal laser endomicroscopy, can be considered as "optical biopsy" in vivo. Of course, endocytoscopy currently is experimental diagnostic method, all available endocytoscopes are prototypes. According to published data, endocytoscopy can be used in precancerous conditions and early intramucosal cancer diagnostics in esophagus, stomach, colon and bronchial tree. Different types of endocytoscopes are used for examinations: some of them are baby-scopes, with fixed magnification 570-1150 times, introduced into accessory channel of the therapeutic parent-endoscope, others--are integrated type, providing scalable magnification from 80 to 380 times. As for traditional pathology ex vivo, for endocytoscopy mucosal cell nuclei stain is needed. For vital staining during endocytoscopy methylene blue, toluidine blue and crystal violet in different concentrations are more often used. In cases of squamous-cell dysplasia or cancer, it is recommended to use 1% methylene blue solution, whereas in intestinal type metaplasia, dysplastic changes and cancer (Barrett's esophagus, P. Correa precancerous cascade, colon adenomas), 1% toluidine blue is preferred. With endocytoscopy, after vital staining, we can visualize and estimate mucosa tissue and cell characteristics: papillae, crypt and gland shapes and sizes, their integrity (tissue markers); cell nuclei size and shape, polarity and nuclear dye intensity (cell markers).