A staining jar is usually referred to in the context of medical science and is used to stain cells and tissues on microscope slides for storage and study ( A microscope slide is a thin flat piece of glass, typically 75 by 25 mm and about 1 mm thick, used to hold objects for examination under a microscope).Most cells appear as a clear substance and therefore the staining jar is used to stain cells for study and research. Stains and dyes are frequently used in biology and medicine to highlight structures in biological tissues for viewing, often with the aid of microscopes and microscope slides. Stains may be used to define and examine bulk tissues,for example, cell populations or organelles within individual cells. These are placed in a staining jar for research in order to qualify or quantify the presence of a specific finding.