Question: Classify and describe epithelial tissue on the basis of structural modifications of cells.
Answer:
There are three types of epithelial tissue on the basis of their structural modifications of cells:
- Squamous epithelium: This type of epithelial tissue are formed by single thin layer of flattened cells with irregular boundaries. This type of tissues are found in the walls of blood vessels and in air sacs in the lungs. The tin cells facilitates diffusion of a substance.
- Cuboidal epithelium: This type of epithelial tissue are formed by single layer of cuboidal cells. This type of tissues are found in ducts of glands and in nephron. Their main function is secretion and absorption.
- Columnar epithelium: This type of epithelial tissues are formed by the single layer of tall and slender cells. Microvilli may be present at the top but their nuclei are present at the base. This type of tissues are found in the lining of stomach and intestine. Their main function is secretion and absorption.
- Glandular epithelium: When cuboidal and columnar epithelium assume specialised function of secretion they are called glandular epithelium. These are found in exocrine and endocrine glands.
- Ciliated epithelium: If cilia are present in cuboidal or columnar epithelium, they are called ciliated epithelium. These are found in bronchioles and fallopian tubes. They facilitates movement of the substances.
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