This assay is optimized for phase contrast images of moving cells such as fibroblasts. Choose this version of chemotaxis assay if your image and cells have similar characteristics as the image below.
Phase contrast microscopy is a technique that takes advantage of a phenomenon called phase shift that occurs when light passes through a transparent object. Invisible to the naked eye, phase shifts arise from the absorption and scattering of light as it hits the sample. It's particularly important in biology as it can show cellular structures that are difficult to detect in any other way without staining the sample.