trypanosomoid form promastigote Any of the bodies representing the morphological leptomonad stage in the life cycle of certain trypanosomatid protozoa resembling the typical adult form of members of the genus Leptomonas, in which the elongate or pear-shaped cell has a central nucleus and at the anterior end a kinetoplast and a basal body from which arises a single long, slender flagellum. BTO:0001124 BrendaTissueOBO