Epithelial Tissue
Epithelial Tissue - Related Videos
01:23
Epithelial Tissues and Their Functions
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2025
Epithelial tissues are large sheets of cells covering all of the surfaces of the body. These surfaces can be internal or external, for example, skin, airways, the digestive tract, the urinary system, and the reproductive system. Hollow organs and body cavities that do not connect to the body's exterior, including blood vessels and serous membranes, are lined by epithelial tissue known as the endothelium. Epithelial tissues provide the body's first line of protection from physical, chemical, and...
06:33
Establishment of Human Epithelial Enteroids and Colonoids from Whole Tissue and Biopsy
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Cited by 132 •
2015
We describe a method to establish human enteroids from small intestinal crypts and colonoids from colon crypts collected from both surgical tissue and biopsies. In this methodological article, we present the culture modalities that are essential for the successful growth and maintenance of human enteroids and colonoids.
08:49
Engineering Three-dimensional Epithelial Tissues Embedded within Extracellular Matrix
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Cited by 6 •
2016
This manuscript describes a soft lithography-based technique to engineer uniform arrays of three-dimensional (3D) epithelial tissues of defined geometry surrounded by extracellular matrix. This method is amenable to a wide variety of cell types and experimental contexts and allows for high-throughput screening of identical replicates.
01:22
Classification of Epithelial Tissues: Overview
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2023
Epithelial tissues are classified according to the shape of the cells and the number of cell layers formed. Cell shapes can be squamous (flattened and thin), cuboidal (square-like, as wide as it is tall), or columnar (rectangular, taller than it is wide). Additionally, the nucleus shape helps identify the type of epithelial cells. Squamous cells have flattened disc-shaped nuclei, cuboidal cells have spherical nuclei, and columnar cells have elongated nuclei. Based on the number of cell layers,...
01:29
Classification of Epithelial Tissues: Stratified Epithelium
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2025
Stratified epithelium consists of several stacked layers of cells. They provide the durability to withstand constant physical and chemical attacks. Stratified epithelium is named after the shape of the most apical layer of cells. Stratified squamous epithelium is the most common type found in the human body. In this tissue, the apical cells are squamous, whereas the basal layer contains either columnar or cuboidal cells. The basal cells divide to form new daughter cells, which gradually become...
FAQs
Polarity gives epithelial cells two functionally different regions: an apical surface facing the outside or a lumen and a basal surface attached to the basement membrane. This orientation positions cellular activities relative to neighboring compartments. As a result, epithelial tissue can maintain organized boundaries while supporting directional protection, absorption, secretion, transport, sensation, or exchange.
Cell junctions hold neighboring epithelial cells together and help preserve the continuity of the layer. This cohesion is essential because gaps could disrupt the separation between body surfaces, internal cavities, organs, or lumens. By maintaining an intact cellular sheet, junctions support barrier function and help epithelial tissue regulate movement between distinct compartments.
The organization of epithelial tissue determines which roles it can perform effectively. Closely arranged cells are suited to forming continuous boundaries, while differences in structure can support protection, absorption, secretion, transport, sensation, or exchange. Examining tissue organization therefore helps connect visible cellular arrangement with the specific demands placed on a body surface, cavity, organ, or gland.
Epithelial barriers regulate movement rather than simply blocking all substances. Their closely packed organization and specialized junctions help separate adjacent environments, while the tissue's selective properties control exchange between them. This regulation supports stable internal conditions by limiting uncontrolled passage and allowing epithelial surfaces to participate in transport, absorption, secretion, or exchange where appropriate.
Within organs, epithelial tissue can form protective boundaries, line internal spaces, or contribute to gland formation. These arrangements allow it to perform different tasks according to location, including secretion, absorption, transport, sensation, and exchange. Considering both the tissue's position and organization helps explain how epithelial structures support the specialized functions of body surfaces and internal organs.
A useful examination focuses on cellular arrangement, the distinction between apical and basal surfaces, attachment to the basement membrane, and the presence of cell junctions. These features reveal how the tissue maintains cohesion and separates compartments. Relating those observations to protection, absorption, secretion, transport, sensation, or exchange provides a functional interpretation rather than a purely structural description.
Epithelial organization provides a framework for studying how body surfaces and organ linings respond when their continuity is disrupted or their function changes. Research can connect alterations in cell arrangement, junction-based cohesion, barrier regulation, or basement-membrane attachment with wound repair and disease processes. This perspective also helps explain how tissues preserve or lose stable internal conditions.