Pseudostratified ciliated columnar epithelium

Nasal epithelium. The nasal cavity superior to the nostrils (vestibule) is covered by skin containing hair follicles and sebaceous and sweat glands. The skin is continuous with the inner nasal mucosa. Posteriorly, the epithelium is a pseudostratified ciliated columnar epithelium that covers the respiratory regions (formed by the maxilloturbinates).45,107,110 The superior turbinate (also called the ethmoturbinate) is lined by a thicker mucosa consisting of olfactory receptors and supporting cells.45,110... 

The pharynx, larynx, trachea and bronchi are lined with pseudostratified, ciliated columnar epithelium that contain at least eight cell types, including mucous secretory goblet and Clara cells, which produce a protective mucus layer of 5-10 jum thickness (see Table 9.2). Subepithelial secretory glands, present in the bronchial submucosa, also contribute to the mucus blanket [9]. Through coordinated ciliary movement a propulsive wave is created, which continuously moves the mucus layer up towards the larynx. Consequently, the mucosal surface of trachea and bronchi is constantly swept to remove inhaled materials. As the bronchi divide into bronchioli, the ciliated columnar respiratory epithelium is much thinner and changes to a simpler non-ciliated cuboidal epithelium. The epithelium in the terminal and respiratory bronchioles consists of ciliated, cuboidal cells and a small number of Clara cells. However, Clara cells become the most predominant type in the most distal part of the respiratory bronchioles [10]. 

Figure 10.1 Typical tracheo-bronchial and bronchiolar epithelia showing the major cell types. The tracheo-bronchial epithelium showing the pseudostratified nature of the columnar epithelium, principally composed of ciliated cells (C), interspersed with goblet cells (G), brush cells (Br), serous cells (S), Kulchitsky s cells (K) and basal cells (B). The bronchiolar epithelium showing the cuboidal nature of the epithelium, principally composed of ciliated cells (C), Clara cells (Cl) and infrequent basal cells. Muc = mucus Ci = cilia N = nucleus Sec = secretory granules.

Nasal 0.015 m fairly accessible Mucus, ciliated, columnar pseudostratified epithelium (10 pm) -h-h-f 2-20%... 

Pulmonary 80-140 m not easily accessible Bronchi and bronchioles mucus, ciliated columnar pseudostratified epithelium (10-60 pm) Alveoli squamous epithelial monolayer ([Pg.262]

In large bronchi the cartilages are irregular in shape but frequent enough to be found in any plane. In small bronchi, they are less frequent and may be missed in transverse section. The bronchioli lack cartilage. The epithelium in the major bronchi and proximal bronchioles is a ciliated pseudostratified epithelium, with ciliated columnar cells as the predominant cell type. In the distal bronchioles the epithelium consists of a single cell layer. The ciliated columnar cells reach the basal lamina with slender basal processes [43]. 

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