**5. Possible cell death modalities in trichomonas**

The biochemical basis for alternative forms of cell death morphologically distinct from PCD continues unknown. Understanding the mechanisms for these forms has implications for the understanding of evolutionary aspects of cell death programs, developmental cell death, neurodegeneration, and cancer therapeutics and for the design of novel therapeutic agents for diseases featuring these alternative forms of cell death [30].

Death of *T. foetus* was observed after higher concentrations of hydroxyurea or zinc, or longer times of serum deprivation [12, 21]. Recent studies show that the molecular events governing tetracyclines induced cell death in trichomonads provided via activating of several specific pathways and genes families [25] which leads to a programmed type of death.

The parasite *T. foetus* submitted to treatment with H2O2 and griseofulvine, demonstrated the induction of mechanisms of a second pathway of cellular death related to autophagy machinery with formation of autophagosomes [4]. When subjected to different treatments such as griseofulvine and PDT, the parasite cytoplasm either shows the formation of autophagic vacuoles, which can be related to the mechanism of autophagic cell death [4, 6]. The process of autophagy is suggested also after treatment of *T. vaginalis* with lycorine, owing to fragments of


