In multicellular organisms cells of similar structure and
function come together to create tissues . Complex organisms
have many different cell types that fulfill different structural
and physiological needs of the organism. There are four basic
tissue types: epithelial types share several common features: -
Cells are typically arranged into continous sheets (with the
exception of glandular epithelium) - The basal surface of the
cells is attached to a basement membrane between the epithelium
and underlying connective tissue - The apical surface is free
(not attached to other tissues) Epithelial tissue is classified
according to the number of cell layers and the cell shape of
each tissue type. Epithelial cells can also be ciliated (with
small hairs) or unciliated Classification of epithelium: Number
of cell layers Epithelium can be simple (a single layer of
cells) or stratified (more than one layer of cells). In general,
simple epithelium is much more delicate than stratified
epithelium and occurs in areas of