Structure and Concentration of Elastic System Fibers in the Trachea of the Rat Estructura y Concentración del Sistema de Fibras Elásticas en la Tráquea de la Rata

and concentration of elastic system fibers in the trachea of the rat. Int. J. Morphol., 29(1):16-21, 2011. SUMMARY: The extracellular matrix is a key element in the tracheal morphology and physiology, both in normal and pathological states, yet little is known regarding its composition and organization. Herein we carried out a detailed study of the morphological organization and volumetric density of elastic system fibers in the trachea of Wistar rats. Six Wistar rats at the age of 45 days were used. The trachea was excised following anesthesia with Thiopental and perfusion through the left ventricle with buffered saline followed by formalin solution. Samples were fixed in formaline, embedded in paraffin, and histologically processed. The elastic system fibers were evaluated at light microscopy by using Weigert’s resorcin-fuchsin technique after oxidation with oxone. Morphometric studies were performed by the point-counting method. Quantities were expressed (%, mean) as volumetric densities and were determined on 25 random fields for each animal. Elastic system fibers were identified beneath the tracheal mucosa showing mainly a longitudinal profile. There were also some bundles of oblique fibers in this region, forming an irregular network of elastic tissue. Close to the inner surface of the cartilaginous ring, a well defined circular layer is present. The volumetric density of the elastic system fibers in the trachea of Wistar rats is 2.46 ± 0.99%. The data in the present study provides original information regarding the elastic system fibers of the rat trachea, which might be used as a model for studying human major airway morphology. The results reported herein provide the basis for continuous investigations on tracheal extracellular matrix by stereology