Excretory-secretory products (ESP) serve as important mediators of intercellular and inter-species communication. They were originally thought to be secreted mainly in a soluble form, but recent discoveries indicate their delivery through extracellular vesicles (EVs). These membraneous particles provide protection from degradation for some of their components, as well as targeted delivery through various receptors on their surface. As such they have been studied as potent immunomodulators in host-pathogen relationships. With respect to parasitic helminths, EVs are being studied as agents for diagnosis, vaccination or therapeutics. However, their general biology, especially their biogenesis patterns, is still poorly understood compared to their functional role.Therefore, the goal of this thesis is to investigate in more detail the secretion activity of EVs in different tapeworms and their life-cycle stages. Under laboratory conditions, the life cycle of Schistocephalus solidus, a tapeworm with an aquatic life cycle, was established to explore EVs secretion at different developmental stages. Moreover, we used proteomic analyses and ultrastructural observations to identify the main biogenesis pathways behind EVs secretion in a terrestrial tapeworm Hymenolepis diminuta. This also allowed for the comparison of EVs generation in tapeworms with different host types