Trachea (histology)

The trachea is a tubular organ that directs air from the larynx further into the bronchi, while improving its properties. The cross-section shows its basic structure: the horseshoe-shaped hyaline cartilage discs, both ends of which are connected by a straight paries membranaceus made of smooth muscle and elastic fibers.

Lamina epithelialis
The trachea is mostly lined by a multilayered cylindrical epithelium with cilia and goblet cells, the number of which increases aborally. Mucus formed by goblet cells and displaced by lashes together forms an important cleansing mechanism. The exception is carina tracheae, which is protected by a more resistant layered squamous epithelium. At the point where the trachea is divided into bronchi, the air flows turbulently, which puts more strain on the mucosa.

Lamina propria mucosae
A layer of very cellular sparse collagenous connective tissue, it contains blood vessels , unmyelinated nerves and seromucinous glands. There are also more or less numerous plasma cells and lymphocytes, which can even form follicles ( BALT ).

Tunica submucosa
Unlike other organs, the submucosa consists of a sparse ligament similar to the lamina propria. Due to this, and due to the absence of muscles of the lamina muscularis mucosae, it is difficult to find the boundary between the lamina propria and the submucosa. Numerous lymphatic infiltration from the lamina propria intervenes here, and larger blood and lymphatic vessels and seromucinous glands are entrapped in the ligament itself.

Tunica fibromusculocartilaginea
Cartilagines tracheales are hyaline cartilages in the shape of a horseshoe, with the ends open in the dorsal direction. Neighboring rings are connected by a dense collagen connective tissue, originating from the perichondria of individual cartilages. The cartilage forms a skeleton of the trachea, without which its lumen would collapse when exhaled.

Paries membranaceus is a skeleton made of smooth muscle (m. Trachealis) and elastic fibers, which complements the open form of cartilage at the back. The tension of the elastic fibers prevents excessive spreading, the rate of muscle contraction regulates the lumen of the trachea.

Tunica adventitia
It consists of a sparse collagen ligament, into which a number of blood and lymphatic vessels and nerves are taken. It connects to the perichondrium (dense collagen connective tissue) from the outside and passes into the interstitium of the surrounding structures of the neck and mediastinum.

Related Articles

 * Larynx (histological specimen)
 * Bronchi (histology)
 * Bronchioles (histology)

Literature

 * EIS, Václav, Štěpán JELÍNEK and Martin ŠPAČEK. Histopathological atlas  [online]. © 2006. [feeling. 2010]. < http://histologie.lf3.cuni.cz/histologie/atlas/index.htm >.


 * JUNQUIERA, L. Carlos, José CARNEIRO and Robert O. KELLEY. Basics of histology. 1st edition. Jinočany: H & H 1997, 1997. 502 pp.  ISBN 80-85787-37-7.