Epithelial cells are present in many different tissues in the body, and possess a diverse number of functional properties. However, all epithelial cells share some common characteristics. The cells possess a morphological polarity (an-apical and basolateral surface), and are interconnected by tight junctions. The epithelial cells also possess the capacity to transport select solutes across the monolayer. Transport systems localized on either the apical or basolateral surface are respon sible for this vectorial transport. Such characteristics of epithelial cells can be examined in the tissue...