I. Introduction
Over the past decade, recent advances in cellular imaging technology have made it possible to capture high-resolution images of cellular structures and processes that enable biologists to investigate fundamental questions in cell structure, morphological development, and cellular disorders. One dynamic structure of interest is the blood-brain barrier (BBB), a selective barrier formed by epithelial cells that is highly restrictive in the transport of substances between the blood and the central nervous system [1]. The epithelial cells found in the BBB form complex tight junctions by the interaction of several transmembrane proteins, such as occludin and claudin, which effectively seal the paracellular space. Paracellular transport can be regulated in response to different conditions, in part through the action of accessory proteins, such as ZO-l, which link transmembrane proteins to the actin cytoskeleton. Disruptions in BBB barrier function have been implicated in several neurodegenerative disorders and can be a consequence of stroke and traumatic brain injury [2]. In vitro systems are needed to understand how the formation and regulation of tight junction structures ultimately affect permeability and transport across the BBB. These data will provide much needed insights for effective drug design and models of disease progression.