Cuboidal epithelium

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]. 

The outer surface of the cornea is covered with a smooth layer of stratified corneal epithelium (Figure 3.4). The lower layer of cells is columnar in shape and rests on a basement membrane that sits on top of a thick limiting structure termed Bowman s membrane derived from the corneal stroma below. The corneal stroma is composed of parallel bundles of collagen fibrils termed lamellae and rows or layers of branching corneal fibroblasts termed keratocytes. The posterior of the cornea is covered with a low cuboidal epithelium with a wide basement membrane (Descemet s membrane) and rests on the posterior portion of the corneal stroma. The corneal epithelium is normally under tension due to the pressure that is present in the anterior chamber just behind the cornea. The intraocular pressure is between 10 and 20 mm of mercury and is enough to cause the cornea to contract about 5% when it is excised from the eye. Therefore this pressure must be transferred between epithelium via cell-cell junctions. 

Eccrine (merocrine) sweat glands are simple tubular glands that open directly onto the skin surface (Figure 35.1). In humans, they are found over the entire body surface except for the lips, external ear canal, clitoris, and labia minora. Myoepithelial cells located in the secretory portion of these glands are specialized smooth muscle cells, which, upon contraction, aid in moving the secretions toward the duct. The eccrine sweat gland duct is comprised of two layers of cuboidal epithelium... 

Bile-duct adenomas are rare. Usually, they are solitary and < 2 cm in size. This type of adenoma is more often detected in men than in women (3 1) and it occurs in patients mainly over the age of 50. It is nearly always localized beneath the liver capsule. This adenoma has the form of a firm, whitish node and consists of bile-duct proliferations. It contains biliary acini and tubules which are lined with a layer of cuboid epithelium within loose fibrous, partially hyaline stroma. There is evidence of mononuclear inflammatory cells and, occasionally, lymph follicles. It is discussed that such biliary adenomas are peribiliary gland hamartomas. (162) There are no clinical or biochemical abnormalities, nor is there any tendency towards malignant degeneration. (161,163)... 

Figure 6. High power view of tubular cysts lined by simple cuboidal epithelium (labeled c). Adjacent tubules show tubular dilatation (labeled d). PAS stain, orig. magn. x 100. (Reproduced with permission from Markowitz etal [100]).

Benign biliary ductular proliferations are seen in a variety of conditions associated with hepatic injury and subsequent metaplastic changes. Bile duct hamartomas (von Meyenburg complexes) are small collections of bile ductules displaying dilated ductules with contour irregularities, single layer of bland, cuboidal epithelium, and intraluminal bile. 

Microglandular adenosis Round glands in fat lined by flat to cuboidal epithelium inspissated secretions within glands Absent Present S-1 00+, EMA-, ER/PR-CCDFP15-... 

The papillary tumor of the pineal region (PTPR) is a rare tumor found at all ages. It has a prealbumin- and CAM5.2-positive cuboidal epithelium wrapped around vessels and closely resembles a choroid plexus tumor. 

Its location in the third ventricle, usually near the choroid plexus and foramen of Monro, helps distinguish the colloid cyst from other cysts that superficially resemble it but that occur in different locations. This cyst s simple columnar and cuboidal epithelium, which... 

Respiratory bronchioles 16-18 262,144 0.5 1.2 534.0 from orders 11-13 Definite class bronchiolar cuboidal epithelium present, but scattered alveoli... 

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