Columnar cells

Cilia are thin cylindrical hair-like structures with a cross-sectional radius of 0.1 gm projecting from the apical epithelial surface of ciliated columnar cells. Ciliary length is thought to correspond to periciliary fluid depth and range from approximately 7 gm in proximal airways to roughly 5 gm in more distal airways.- Each ciliated epithelial cell supports approximately 200 cilia at a density of eight cilia/gm. Short microvilli, possibly associated with secretory functions, are interspersed among the cilia. 

The highly vascularized respiratory epithelium is composed of five major cell types ciliated cells, nonciliated cells, columnar cells, goblet cells, and basal cells. Low numbers of neurosecretory cells are present in the basement membrane [17]. Approximately 20% of the total number of cells in the lower turbinate area is ciliated with fine projections ( 100 per cell) on the apical cell surface. Cilia are used to transport the mucus toward the nasopharynx. These long (4-6 fxm) and thin projections are mobile and beat with a frequency of 1,000 strokes per min. Ciliated and nonciliated columnar cells are populated with about 300 microvilli per cell, which help in enlarging the surface area. 

The characteristics of the nasal lesions in mice following chronic inhalation of ethylene dibromide were investigated. Male and female B6C3F, mice were exposed to 10 or 40 ppm [77 or 308 mg/m- ] ethylene dibromide for 6 h per day on five days per week for 103 (10 ppm) or 90 (40 ppm) weeks. The incidence of hyperplastic lesions was related to the dose of ethylene dibromide and was equivalent in males and females. Lesions consisted of focal areas of cuboidal to columnar cells arranged in a glandular pattern with foci of hyperplastic squamous epithelium also seen occasionally. Lesions were usually located in the anterior (respiratory turbinates) of the nasal cavities. A broad spectrum of proliferative lesions was observed (Stinson et al., 1981). 

The corneal epithelium in itself is also a layered structure, 50-100 pm thick, consisting of a deep layer of basal columnar cells, an intermediate layer of polyhedral cells, and a surface layer of squamous, polygonal-shaped cells. The outermost cells have skirting intercellular junctions, termed tight junctions (Figure 25.3). These form a strong barrier to nonlipophilic substances, allowing the preferential penetration of nonionized forms. 

The stomach has a surface epithelium composed of a single layer of columnar cells with few apical microvilli. The epithelial lining of the small intestine consists of a single layer of columnar cells with densely packed microvilli to promote absorption. The epithelium in the large intestine is similar to that in the small intestine except for the absence of villi in the large intestine. 

The cervical section presented in Fig. 10.7 has been diagnosed as a rare form of neoplasma known as villoglandular adenocarcinoma. Characteristic cytologic features of this condition include the presence of long villous fronds and papillae lined by columnar cells with intact cytoplasmic borders and minimal atypia.32 Three-dimensional ball-like clusters of cells with smooth intact communal cytoplasmic rings are also associated with this condition.32... 

Conducting airways Trachea 0 20-18 Pseudostrati fled cell Ciliated cell Columnar cell Goblet cell Serous cell Mucous cell 20-40... 

Immunoglobulin A (Fig. 11.3) is the major immunoglobulin present in intestinal secretions. It is synthesised in the lamina propria by local plasma cells and is found there in the dimeric form (IgA)2, which is transported into the intestinal secretions by two pathways. Firstly, it diffuses from the site of synthesis into the columnar cells of the gut and here it forms a remarkable... 

Columnar cells Basement membrane Protects mouth... 

The mouth and esophagus are composed of two layers, the mucosa and submucosa (Figure 3.5). The mucosa is lined on its outer surface by a stratified squamous epithelium with layers of polyhedral cells of the intermediate layers and low columnar cells of the basal layer. Below the cellular layer is the lamina propria containing loose connective tissue with blood vessels and small aggregates of lymphocytes. Smooth muscle within the mucosa (muscularis mucosal layer) is seen as small bundles. The submucosa... 

Lining Epithelium Columnar Cells with Striated Borders and Goblet Cells... 

Figure 9.2 Diagram of the four cell types in the nasal respiratory epithelium. A ciliated columnar cell covered by cilia and microvilli of uniform length B basal cell C goblet cell packed with mucus granules D nonciliated columnar cell, covered by microvilli of uniform length. (Redrawn from Mygind, N., 1979 Nasal Allergy, 2nd edition. Blackwell Scientific Publications Oxford).

In some cases, cells in a persistently stressful environment may be replaced by a cell type that is better able to withstand the harsh environment. Replacement of an adult cell type by another adult cell type is known as metaplasia and is usually a reversible change. Perhaps the best-known example of metaplasia is the replacement of the normally tall (columnar), ciliated epithelial cells in the respiratory tract of cigarette smokers by layers of relatively flattened (squamous) epithelial cells. While the squamous epithelial cells are somewhat tougher than the columnar cells, important functions such as mucus secretion are lost. In addition, the continued stresses that induce metaplasia may lead to neoplastic transformation. 

Odontoblasts more or less columnar cells on the outer surface of the pulp of a tooth specialized cells that contribute to many aspects of tooth structure and function. They give rise to the dentine matrix that underlies the enamel of a tooth Otoliths earstones, are small calcareous structures found in the head of all bony fishes (other than sharks, rays, and lampreys)... 

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