(a) The cellular microenvironment is composed of different cell types, biochemical cues, and mechanicals cues. Each of these components can be arranged in numerous combinations that (b) organize into tissues with unique architectures, structures, and functions. (c) Cellular ecology encompasses all levels of an organism, from single molecules to whole organs. An example of tissue hierarchy is shown as follows: biochemical molecule → epithelial cell → glomerulus → kidneys → human. Some art elements from Servier Medical Art that are registered under a CC BY license.