Illuminating Cells: Mechanistic Heuristics in the Age of Fluorescence Microscopy

Abstract This article draws on and extends Bechtel’s influential work on the historical and philosophical implications of mechanistic research in cell biology. Beginning in the 1940s, cell biology relied on electron microscopy (EM) and cell fractionation, exemplifying the coupled epistemic strategies of structural decomposition and localization through experimental engagement with component parts and operations (Bechtel and Richardson [1993]2010; Bechtel 2006). In the 1970s, however, fluorescence microscopy (FM) enabled visualization of proteins and macromolecular assemblies in intact cells, which transformed mechanistic studies in cell biology. Through a historical analysis of cell adhesion and migration research, we show how the development and use of FM enabled what we call exposition of mechanisms. Instead of physically de composing cells into component parts, FM allowed researchers to visually ex pose these parts directly in their spatial-functional context in intact and even living cells . This epistemic strategy retained the mechanistic assumption that living systems can be meaningfully studied through localizable parts and operations. Yet, FM allowed for a more holistic approach to investigate structurally integrated components of minimally decomposable systems, such as focal contacts and the cytoskeleton, thus illustrating the importance of preserving the cellular context.