Staining Techniques

Staining is one of the most important practical techniques in cell biology, because it is often the only way to actually see different components of a cell clearly at all - each part of the cell has a different chemical affinity for different dyes, and the general technique of deliberately staining cells and tissues to reveal this difference is called histochemical staining, or histochemistry. In practice, a fixed set of well-established stains is routinely used, because each one has become closely associated with revealing one particular cell component: eosin stains the cytoplasm and cellulose pink or red; acetocarmine and haematoxylin both stain the nucleus and chromosomes pink or red; methylene blue stains the nucleus blue; safranine stains lignified cell walls red; cotton blue stains fungal hyphae blue; Sudan IV and Sudan Black stain lipids scarlet-red or black respectively; Coomassie brilliant blue stains protein blue; Janus Green specifically stains mitochondria a greenish-blue; I2KI (iodine-potassium iodide solution) stains starch a bluish-black to brown colour; and toluidine blue stains xylem, parenchyma and epidermal tissue blue or greenish-blue. Choosing the right stain for the struct …