 We turn now from questions about the ontological status of cells to epistemic questions about how scientists study them. We begin with how scientists represent cells and information about them. Traditionally, philosophy of science has focused on linguistic representations of scientific knowledge. But in many fields of biology and especially in cell biology, information is often presented in images. Scientists’ very familiarity with cells results from visual representations generated using microscopes. Developing microscopes and techniques for using them to produce interpretable images presented a number of challenges. We begin in section 4.1 with the challenges in generating images (micrographs) at all and in section 4.2 consider challenges in evaluating the reliability of the resulting images. Beyond these replete (highly detailed) representations, cell biologists rely on a variety of less replete diagrams. (The characterization of images as “replete” is due to Perini, 2013. Drawing on Goodman, she uses relative repleteness to differentiate diagrams from pictures.) In particular, as discussed in  section 4.3,  when they are developing mechanistic hypotheses about cells, cell biologists rely on cell diagrams that represent types of cell components and mechanism diagrams that represent select components within cells that are hypothesized to constitute parts of the mechanism responsible for a given phenomenon (Downes 1992).