Single-layer single-row epithelial tissues may include various forms of epithelial cells. So, they can be prismatic, cubic, flat.
Endothelium and mesothelium represent a single-layer flat tissue in the body.
Serous membranes are covered with mesothelium (peritoneum, pleura, pericardial sac). Mesothelial epithelial cells have uneven edges and a polygonal shape. Through mesothelium, the absorption and release of serous fluid is carried out. Its smooth surface provides easy glide of internal organs. Mesothelium also prevents the occurrence of adhesions between the abdominal or thoracic organs, the development of which can occur with its complete violation.
The endothelium is lined with lymphatic and blood vessels. It is represented by flat epithelial cells (endotheliocytes). They form a single layer on the basement membrane. The endothelium is located in vessels on the border with blood or lymph and takes part in the exchange of gases and substances between these vessels and other tissues. Its damage provokes a change in vascular blood flow and the formation of blood clots in the lumen.
Part of the tubules of the kidneys is lined with a single-layer cubic epithelium. It provides reverse absorption (reabsorption) of certain substances into the blood from primary urine.
Tissue, including prismatic epithelial cells, is characteristic of the middle digestive section. They are lined with the inner gastric and intestinal surface, some liver ducts and pancreas, gall bladder. Epithelial cells are connected by desmosomes, slot communication connections, like a lock, by tight closure connections. Due to this, the contents of the intestinal and gastric cavities do not penetrate into the tissue gap.
The airways are lined with multi-row epithelium, which are ciliated and contain various shapes and perform different cell functions.
The cornea of the eye is outside, the esophagus and the oral cavity are covered with a multilayer flat tissue. This epithelium includes three layers: flat (superficial), basal and intermediate (prickly).
A multilayer flat keratinized tissue covers the skin surface. Thus, cutaneous epidermis is formed. The keratinization process is carried out here, which is associated with the differentiation of epithelial cells. The epidermis includes several layers. This includes a prickly, basal, horny, granular and shiny cell layer. The last three layers in the skin of the soles and palms are especially pronounced.
Transitional epithelium (multilayered) is typical for urinary organs (renal pelvis, bladder, ureter). There are several layers here: surface, intermediate, basal layer. Epithelial cells in urine (urinary sediment) are almost always found. The norm is their content of not more than ten in the field of view. The indicator is detected using a general urine test.
The integumentary tissue occupies a “borderline” position. This tissue is under the constant influence of the external environment, therefore, its cells wear out and die relatively quickly. Recovery occurs due to stem cells. They have the ability to divide and maintain it throughout the life of the body.
Epithelial tissue is quite well innervated. It includes receptors (nerve endings with sensitivity) in large numbers.
The epithelium lines the cervix and vagina. Its increase depends on the increase in the content of female hormones in the body. Epithelial cells in the smear from the vagina are normally present. Their number varies depending on the hormonal drugs used, the phase of the menstrual cycle. A lack of cells may indicate tissue atrophy, a lack of estrogen, or an excess of male hormones.