The Multisizer 4e COULTER COUNTER is a highly versatile particle counting and characterization system. It utilizes the Coulter Principle to detect particles via electrical zone sensing regardless of the nature or optical properties of the particle. As such the Multisizer 4e is an ideal tool for detecting and counting a wide variety of particles such as mammalian cells, bacteria, yeast, abrasives, toner particles, cell aggregates, spheroids and even large protein aggregates. The Multiszier 4e COULTER COUNTER detects cell size and volume changes event if they happen over a few seconds or in a period of several hours. Change in cell volume is an important factor involved in many biological processes such as Cell Growth, Cell Cycles, Cell Death, Compensation for Osmotic Stress, Pathogenesis and Phagocytosis