Stratified Epithelium
What is It?
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Classifications
- Squamous
- "flat"
- form cell layers of the alveoli and the lining of the esophagus
- Columnar
- "column-shaped"
- forms cell layers of the ocular conjunctiva and the linings of the pharynx, anus, uterus, urethra, and vas deferens
- Cuboidal
- "cube-shaped"
- forms surface of the epidermis and the lining of mouth
Stratified Squamous Epithelia
Image from: http://www.pathguy.com/histo/090.jpg.Permission pending. |
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Stratified Columnar Epithelia
Image from: http://www.cytochemistry.net/microanatomy/epithelia/salivary8.jpg.Permission pending. |
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Stratified Cuboidal Epithelia
Image from: http://www.kumc.edu/instruction/medicine/anatomy/histoweb/epithel/small/Epth017s.JPG.Permission pending. |
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Specializations
- keratinized
- apical layers
- dead
- no nucleus or cytoplasm
- keratin - water-resistant protein
- found primarily in skin
- transitional layers
- able to stretch
- without distention (relaxed), the cells appear cuboidal-shaped
- when distented (tense), the cells appear squamous-shaped
- impermeable to salts and water
- found in urinary bladder, ureter, and pelvis of kidney
- urine/fluid builds up in these cavities, the transitional layers extend to relieve the stress
Resources
http://ect.downstate.edu/courseware/histomanual/epithelia.html
http://www.cytochemistry.net/microanatomy/epithelia/stratified_squamous.htm
http://www.cytochemistry.net/microanatomy/epithelia/stratified_columnar.htm
http://www.courseweb.uottawa.ca/medicine-histology/english/ss_basictissues/epithelia.htm