Amastigotes are forms of Leishmania, naturally occurring in vertebrate hosts within phagocytic cells - especially the macrophages. The aim of this project was to compare three types of amastigotes of Leishmania that can be used for experiments under laboratory conditions - namely the axenic amastigotes, cultured extracellularly (without vertebrate phagocytic cells), amastigotes isolated from macrophages infected ex vivo, and "true" amatigotes isolated from lesions of the infected BALB/c mice. Amastigotes were compared with respect to the development in the natural vector and at the proteome level. L. mexicana, the causative agent of cutaneous leishmaniasis in the New World, was chosen for this comparison. In experiments comparing the development of Leishmania in the natural vector Lu. longipalpis we found significantly weaker infections in the sand flies infected with axenic amastigotes compared to other types of amastigotes. In addition to the intensity of infection, we compared the localization of promastigotes in the digestive tract of the phlebotomine sand flies. The following localizations were observed: the abdomen, the thorax, the cardia and the stomodeal valve, which is crucial for infectivity of the sand fly. There was no significant difference in localization in any of the groups of...