RESUMEN
Biological research, including clinical trials, mainly uses animals as model organisms. Currently, animal experimentation remains controversial for several reasons, namely the implementation of animal protection and ethics panels, the high costs and the long duration of experiments. These constraints encourage researchers to use alternative methods in order to overcome these barriers. The ciliate Tetrahymena is a unicellular eukaryotic organism that has contributed significantly to the acquisition of knowledge in the field of fundamental biology. Characterised by a well-ordered structure and a short life cycle, the protozoan Tetrahymena is very commonly used in the laboratory due to the ease involved in handling it. Therefore, this organism has allowed researchers to elucidate a number of mechanisms in higher organisms including mammals. This bibliographic review describes the favourable biological characteristics of the protozoan Tetrahymena as well as various physiological and molecular studies that have been carried out on this organism. Studies have shown that Tetrahymena is one of the alternatives to animal experimentation and a major contributor to the development of biological and life sciences.