BIO 135 Virtual Labs

Epithelial Tissues Identification Guide

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	Simple Squamous Epithelium Identification: Small, flat cells arranged around large, empty circles (air sacs). May be confused with Adipose Tissue, but note the multiple cells and nuclei (arrows). Features to Know: nuclei. Where Located: lung (air sacs or alveoli) and lining blood vessels . Function: diffusion (gas exchange). The top image is what you would see with a transverse section through the tissues. The bottom image is from a cheek smear and shows a cluster of four cells viewed if they were laid out flat.
	Simple Cuboidal Epithelium Identification: Squarish cells with round nuclei in a single row (arrows), usually arranged in a circle (tubule). Features to Know: nuclei. Where Located: kidney tubules (can also be seen in sweat glands of skin slide). Function: absorption and secretion.
	Simple Columnar Epithelium Identification: Tall rectangular cells, with single, neat row of oval nuclei, usually more towards the base (in the bracketed row, the base is towards the top), leaving an apical region of nucleus-free cytoplasm. Note also goblet cells, found only here and in Pseudostratified Columnar Epithelium. Features to Know: goblet cells (1), nuclei (2), microvilli (3). Where Located: jejunum of small intestine. Function: absorption and secretion.
	Pseudostratified Columnar Epithelium Identification: Tall rectangular cells, with multiple irregular rows of nuclei (bracketed; compare to simple columnar, above). Note also goblet cells, found only here and in Simple Columnar Epithelium. Features to Know: cilia (1), goblet cells (2), nuclei (3). Where Located: trachea. Function: secretion and movement of mucus.
	Stratified Squamous Epithelium Identification: Many layers (6 or more) of small, flattened cells. The only other epithelial tissue with so many layers is transitional (below), but note that stratified squamous epithelium typically has a more evenly contoured surface; with the uppermost layers of cells flattened. Features to Know: nuclei, if evident. Where Located: lining mouth and esophagus. Function: protection from abrasion and infection.
	Transitional Epithelium Identification: Numerous layers of cells of varying and often irregular shape, though generally not squamous (when unstretched as in the slides). Surface of tissue is folded (inside of ureter) or bumpy appearing (urinary bladder). Features to Know: nuclei. Where Located: ureter (and urinary bladder). Function: elasticity: stretch and retract.

You will not need to know either stratified cuboidal or stratified columnar epithelia in lab.

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This page created by Udo M. Savalli. Maintained by Bill D. Snyder Last updated September 23, 2009