What procedures may be required to prepare a sample for cellular staining?

There are 4 main steps to follow in order to prepare a sample for cellular staining: permeabilization, fixation, mounting, and staining, in that order respectively. During permeabilization, cells are treated with a mild surfactant. This dissolves the cell membranes to allow larger dye molecules to move inside the cell. During fixation, cells or tissue morphology become “fixed” or preserved. Typically, a chemical fixative (which has chemical bonds to increase rigidity) is added. Common fixative agents include methanol, formaldehyde, ethanol and picric acid. Mounting involves affixing samples onto a glass microscope slide for analysis. Cells can be grown directly onto the slide or loose cells may be affixed using sterile techniques. Thin slices of material, like tissue, may be affixed onto a microscope slide as well. Staining involves the application of stains to a sample to color cells, components, tissues, or metabolic processes. Samples become immersed in a dye solution and then are rinsed. The sample can then be analyzed under a microscope. Some dyes may require a mordant, in which the mordant stain will stay on the sample when surplus dye solution is rinsed away.