This document discusses the specializations of epithelial cells. It describes the three main domains - apical, basal, and lateral. The apical domain contains structures like cilia and enzymes. The basal domain attaches to the basement membrane and contains infoldings. The basement membrane is made of collagen and laminin. Junctions between cells include tight junctions, adherens junctions, and desmosomes. Gap junctions allow cell-to-cell communication. Epithelial cell specializations allow functions like barrier formation, regeneration, and transport of fluids.