EM of a striated border in intestinal epithelium. At the lumen (*), apical surfaces of two simple columnar epithelial cells are studded by uniform, closely packed microvilli (MV) covered by a fuzzy glycocalyx (Gl). Many densely packed cytoplasmic organelles include mitochondria (Mi), rough (RER) and smooth (SER) endoplasmic reticulum, and lysosomes (Ly). A junctional complex—tight junction (arrow), intermediate junction (rectangle), and desmosome (circle)—attaches lateral cell borders. 36,000×.