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Simple columnar epithelium is a single layer of columnar epithelial cells which are tall and slender with oval-shaped nuclei located in the basal region, attached to the basement membrane. In humans, simple columnar epithelium lines most organs of the digestive tract including the stomach , and intestines .
Some columnar cells are specialized for sensory reception such as in the nose, ears and the taste buds. Hair cells in the inner ears have stereocilia which are similar to microvilli. Goblet cells are modified columnar cells and are found between the columnar epithelial cells of the duodenum. They secrete mucus, which acts as a lubricant.
Enterocytes, or intestinal absorptive cells, are simple columnar epithelial cells which line the inner surface of the small and large intestines. A glycocalyx surface coat contains digestive enzymes. Microvilli on the apical surface increase its surface area.
Epithelial cells line body surfaces, and are described according to their shape, with three principal shapes: squamous, columnar, and cuboidal. Squamous epithelium has cells that are wider than their height (flat and scale-like). Cuboidal epithelium has cells whose height and width are approximately the same (cube shaped).
Another important cell type is the pulmonary neuroendocrine cell. These are innervated cells that only make up around 0.5% of the respiratory epithelial cells. [7] The ciliated cells are columnar epithelial cells with specialized ciliary modifications. The ciliated cells make up between 50 and 80 per cent of the epithelium. [8]
Ciliated pseudostratified columnar epithelium is the type of respiratory epithelium found in the linings of the trachea as well as upper respiratory tract, which allows filtering and humidification of incoming air. [1] Non-ciliated pseudostratified columnar epithelia are located in the prostate [2] and membranous part of male vas deferens.
Terms used to describe the shape of the cells in it - columnar if column-shaped, and squamous if flat. In the oesophagus , pharynx and external anal canal the epithelium is stratified, squamous and non-keratinising, for protective purposes.
A brush border (striated border or brush border membrane) is the microvillus-covered surface of simple cuboidal and simple columnar epithelium found in different parts of the body. Microvilli are approximately 100 nanometers in diameter and their length varies from approximately 100 to 2,000 nanometers.