Definition of guano. : a fertilizer containing the accumulated excrement of seabirds or bats; broadly : excrement especially of seabirds or bats.
Developmental Biology Online. Epithelial tissues come in three basic types: squamous, cuboidal and columnar. These three types of tissue are seen in either simple (only one cell layer thick) or stratified (many cells in thickness) arrangements.
In pseudostratified columnar, not all the cells appear to reach from top to bottom and nucleus is found at different levels giving it a layered appearance 6. The bottom (basal) layer of stratified epithelial tissue may have different cell shapes from the top (apical) layer.