Monday, September 27, 2010

Human Epithelia




Simple Squamous Epithelium ^
Characteristics: Single layer of flattened cells with disc-shaped nuclei and sparse cytoplasm.
Examples: Present in the kidney glomeruli, lining of heart, blood vessels, lymphatic vessels, and serosae.



Simple Cuboidal Epithelium ^
Characteristics: single layer of cube like cells with large, spherical central nuclei.
Examples: Present in kidney tubules, ducts and secretory portions of small glands, and ovary surface.




Simple Columnar Epithelium ^
Characteristics: Single layer of tall cells with oval nuclei; many contain cilia
Examples: Small bronchi, uterine tubes, and some regions of the uterus




Pseudostratified Columnar Epithelium ^
Characteristics: Single layer of cells with different heights; some do not reach the free surface.
Examples: Male sperm- carrying ducts (nonciliated) and trachea (ciliated)




Stratified Squamous Epithelium ^
Characteristics: Thick membrane composed of several layers of cells
Examples: Forms the external part of the skin's epidermis (keratinized cells), and linings of the esophagus, mouth, and vagina (nonkeratinized cells)





Stratified Cuboidal Epithelium ^
Characteristics: Rare in the body, typically 2 cell layers thick
Examples: Swear and mammary glands




Stratified Columnar Epithelium ^
Characteristics: Limited distribution in the body
Examples: Pharynx, male urethra, lining some glandular ducts




Transitional Epithelium ^
Characteristics: Several cell layers, basal cells are cuboidal, surface cells are dome shaped
Examples: Lines the urinary bladder, ureters, and part of the urethra

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