All epithelial tissues are found on a surface. They are distinguished from each other by their differences in cell shape and cell orientation. In all cases the cells are tightly connected. The following micrographs are available:
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These cells come off the stratified squamous epithelial
tissue on the inner surface of the cheek. These cells show
the irregular, flat shape characteristic of typical
"squamous cells." The nucleus (A) is centrally
located, the cell membrane (C) is very thin, and the
cell is filled with cytoplasm (B). |
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This piece of frog skin allows us to observe the
irregular shape of and close knit nature of the cells that
make up simple squamous epithelial tissue. A - cell
membrane B - nucleus, C - cytoplasm,. |
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At the left, simple squamous tissue (A) line the walls of blood vessels; at the right it makes up the lung alveoli (A) wall.In both cases the cells are very thin.
Locations: Capillary walls, alveoli of the lungs, covering visceral organs, lining body cavities
Function: diffusion and filtration
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In kidney tissue we find the kidney's tubules cut such
that they appear as rings of cells around empty spaces.
These cuboidal cells (A) that line these tubules are
as wide as they are tall as they are deep - cuboidal. The
nuclei (B) are easily observed. |
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The villi of the small intestine are lined by a single
layer of columnar cells (A) - thus the name simple
columnar epithelium. Note these cells are not as wide as
they are tall with the darkly stained nuclei (B)
located at the base of the cells.The cell membranes (C)
are very thin but easily identified. Function: protection, secretion and absorption |
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Line A cuts through this epithelium. The columnar
cells of this tissue all begin at the basement membrane;
only a few reach the surface. The nuclei (C)
appear at various levels giving the tissue a stratified
appearance. The cilia (B) are easily seen.The mucus
producing goblet cells are not visible in this
micrograph.(The pseudostratified ciliated columnar epithelium
you observed in the laboratory was not as "deep" as seen here and included
globlet cells.) |
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The bracket labeled A marks the stratified squamous epithelium.The many layers of cells that make up this tissue are easily seen with higher magnification (right). Observe that the surface cells (at B) are flattened (are squamous). Compare this with the transitional epithelium below.
Location: mouth, vagina, esophagus, anal canal
Function: protection
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At the left observe the ureter is lined by transitional epithelium (A). At the left the epithelium is more highly magnified. Note that the cells at the exposed surface (A) are large and rounded. They are also larger than the cells at the attached surface (B). (Compare this tissue to Stratified Squamous which has squamous cells at its exposed surface.)
Loctions: ureter, urinary bladder
Function: distention
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All micrographs are the property of Sherri Wick. Students of Biology 2740 and 2840 are welcome to use this page in the study and review of lecture and lab materials in the Human Physiolgoy and Anatomy courses.
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