Semifine cross-section of trachea stained with toluidine blue and observed with the objective of 40x. This image shows the different layers that constitute the trachea: mucous, constituted by pseudostratified prismatic epithelium, submucous, formed by connective tissue containing abundant blood vessels, and glands. Details of the mucous and the glands are observed in other microphotographies (zones framed in red and blue respectively)