Final answer:
Polarity in epithelial tissues refers to the differences in structure and function between the apical and basal surfaces of the cells. This includes the segregation of organelles and proteins, as well as the presence of specialized structures on the apical surface.
Step-by-step explanation:
When referring to epithelial tissues, polarity refers to the differences in structure and function between the exposed or apical facing surface of the cells and the basal surface close to the underlying body structures. This means that the cells have distinct characteristics and perform different functions depending on their position within the tissue.
One aspect of polarity in epithelial tissues is the segregation of organelles and membrane-bound proteins between the basal and apical surfaces of the cells. For example, certain organelles may be located on the basal side while others are found on the apical surface. This organization allows the cells to carry out their specific functions effectively.
Another aspect of polarity is the presence of specialized structures on the apical surface, such as cilia. These structures play a role in functions such as movement of substances over the epithelial surface or sensing changes in the environment.