Measurement of cell growth by direct methods

Hemocytometer The hemocytometer is a device used to count cells. The hemocytometer was invented by Louis-Charles Malassez and consist of thick glass Microscope slide with a rectangular indentation that creates a chamber. i) The gridded area of the hemocytometer consists of nine 1x1 mm2 . ii) These are subdivided in 3 directions; 0.25 x 0.25 mm (0.0625 mm2), 0.25 x 0.20 mm (0.05 mm2) and 0.20 x 0.20 mm (0.04 mm2). iii) The centralsquare is further subdivided into 0.05 x 0.05 mm (0.0025 mm2) squares. iv) The raised edges of the hemocytometer hold the coverslip 0.1 mm off the marked grid, giving each square a defined volume.

Hemocytometer grid

Coulter counter The Coulter counter is an apparatus for counting and sizing particles in electrolytes. It is used for cells, bacteria, prokaryotic cells and virus particles. i) The Coulter principle states that particles pulled through an orifice, concurrent with an electric current, produce a change in impedance that is proportional to the volume of the particle traversing the orifice. ii) The Coulter principle was named for its inventor, Wallace H. Coulter. iii) The principle has found commercial success in the medical industry, particularly in hematology where it can be applied to count and size the various cells that make up whole blood.

Coulter Principle