cuboidal cells appear square in side view with nucleus in a central position

Cuboidal cells appear square in side view with

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cuboidal -- cells appear square in side view with nucleus in a central position columnar -- cells appear rectangular in side view with the nucleus displaced toward the base of the cell. If the epithelial cells are arranged in one single layer, the epithelium (plural, epithelia) is considered to be simple ; if they are arranged in two or more layers, it is stratified . Combining these two forms of classification (number of layers and shape of the cells) leads to the following examples of epithelium: 1) simple and stratified squamous; 2) simple and stratified cuboidal; 3) simple and stratified columnar and 4) pseudostratified Figure 3: Some types of simple epithelia. MICROSCOPIC OBSERVATIONS OF ANIMAL TISSUES Basic Tissue Types 3
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Epithelial Tissue: Animal tissues are organized into organs. Hence, to study animal tissues, especially epithelium, sections through organs often must be examined. In this case, only part of the histological sample is the epithelium of interest. Use the schematic diagrams to locate the position of the epithelium before trying to recognize the characteristics of the tissue. a) Simple Columnar Epithelium : Examine the slide which is a cross section through the small intestine. Locate the inner (next to the lumen or cavity) surface of the small intestine. This surface is lined with simple columnar epithelium. This type of epithelium appears as a single layer of tall, column-shaped cells with oblong nuclei. The primary function of this type of epithelium is absorption of nutrients, secretion of digestive juices as well as secretion of mucus by goblet cells. The surface area of the small intestine is increased by outward finger-like extensions and inward indentations, known respectively as villi and crypts (Figure 5). Both of these structures are lined with simple columnar epithelium. In addition to villi (singular, villus) and crypts, find goblet cells , which appear as white, oval cells found among the columnar cells (Figures 4, 5). Figure 4 : Schematic representation of simple columnar epithelium. Figure 5A : The inner surface of the small intestine showing villi and crypts. Figure 5B : Microscopic view of the inner surface of small intestine. 4
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Villus in cross section. Structures labeled "G" are goblet cells. What is the specific function of villi? The function of villi increases the surface area of the intestine so as to increase its capacity to absorb nutrients and liquid from food passing through it. What is the specific function of goblet cells? Goblet cells secrete mucus. b) Simple Cuboidal and Simple Squamous Epithelium - Examine the slide which is a thin section through the kidney. The kidney is composed of thousands of microscopic tubular structures called nephrons, which function in the formation of urine. Figure 6 illustrates the basic structure of the nephron. The most common types of epithelia present within the nephron are: simple cuboidal and simple squamous (Figure 7A). The specific function of the simple cuboidal epithelium is secretion and absorption. This type of epithelium is also found in thyroid gland,
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