Epithelial Tissue

Epithelial Classifications- Epithelial tissues can be classified in two ways, depth and shape.

(1) Depth-

• simple- one layer of cells.
• stratified-multiple layers of cells.

(2) Shape-

• squamous- flat, uneven shaped (like a fried egg)
• cuboidal-cube-shaped
• columnar-long, tall, skinny columns

Epithelial Tissue Type	Photo	Schematic
Simple Squamous one layer of flat, egg-shaped cells found in lining of blood vessels, parts of the kidneys, and lymph vessels involve diffusion & filtration; they are good at letting things across
Simple Cuboidal single layer of cube-shaped cells secretion & absorption ovary surface, secretory portions of small glands, kidney tubules
Simple Columnar single layer of tall, skinny cells many have cilia, which help move something in the cell's environment past it. Cilia are found in bronchi, nasal passageways, and fallopian tubes. Sometimes have goblet cells-mucus secreting unicellular glands.
Stratified Squamous Function: Protection May be keratinized-have lots of keratin, in flat, hard, multiple layers, or it may be nonkeratinized. Keratinized-found on the surface of the skin. Nonkeratinized-found in places where you want protection, but don't want the tissue to be tough. i.e. esophagus, mouth, and vagina.
Pseudostratified Columnar Ciliated w/ goblet cells: respiratory tract. Nonciliated w/ goblet cells: digestive tract. Nuclei are at different positions within the same layer.
Transitional Stratified No goblet cells. Has no clear cell shape-it changes shape due to expansion. Allows stretching of the urinary bladder lining.
Stratified Cuboidal Multiple layers of cube-shaped linings. Rare. Found in: sweat glands & mammary glands.
Stratified Columnar Rare Multiple layers of columns

* Note- the tissue photos and schematics on this page were taken from Delta College Biology Professor Mark Robertson's histology website. http://www.delta.edu/mgrobert/Histology.html