I. Introduction
Cells in living tissue are engaged in continual communication with one another, sending and receiving a host of signals that combine to determine the function of individual cells as well as the emergent behavior of the larger tissue. The structural arrangements of cells define spatial relationships that strongly influence signal propagation. For example, certain forms of signaling (cadherins, gap junctions) typically require membrane-to-membrane contact and are thus confined to directly neighboring cells. On the other hand, secreted soluble factors can diffuse much farther, with signal intensity being modulated by transport-related factors such as distance, barriers to transport, and competitive consumption by other cells. Cellular spatial organization therefore plays a fundamental role in modulating intercellular communication for both contact-dependent and contact-independent signaling pathways [1], [2].