Polarity: basal surface- lower/attached, apical surface- upper/free. Supported by the basement membrane- double layered: superior basal lamina abutting the epithelial tissue, deeper reticular lamina abutting the underlying connective tissue. Avascular (lack blood vessels) but innervated (supplied by nerves) High regenerative capacity (undergo cell division) as long as they receive nutrients and substances from the underlying connective tissue. Cell arrangement: simple- single layer of cells, stratified- 2+ layers of cells. Named according to the cell type at the apical surface. Simple squamous: location: blood vessels, function: filtration (allows substances to pass through blood vessels) Simple cuboidal: location: kidney tubules, function: secretion and absorption. Simple columnar: location: lining of the digestive tract, function: secretes mucus. Pseudostratified columnar: location: lines trachea, function: secrete mucus. Stratified squamous: location: lining of esophagus, function: protection. Stratified cuboidal: location: sweat glands, function: protection. Stratified columnar: location: male urethra, function: protection. Endocrine glands- secrete their products (hormones) directly into the extracellular fluid.