Tetrahymena pyriformis

Tetrahymena pyriformis is a freshwater, eucariotic, unicellular protozoa belonging to the ciliates. The body of tetrahymena pyriformis is generally 50-60 µm long and 30 µm wide and is pear-shaped, a characteristic from which the name of the species is derived. Various modifications of the form are possible in old or stressed cultures. Eighteen longitudinal rows of cilia calles kinetics cover the cell surface. It is the most common protozoan model used in toxicological studies. It is characterised by short life cycle, which allows easy cultivation in suitable laboratory conditions. The toxic effects of substances on several generations can also be tested.