noun, plural: promastigotes
(protistology) The developmental stage or the morphological form in the lifecycle of trypanosomatids characterized by the presence of the flagellum that is located anterior of the nucleus and free from the cell body
A group of kinetoplastid protozoa is called trypanosomatids. This group is known for their different morphological forms throughout their life cycle. These morphological forms or stages in their life cycle are the following: (1) amastigote, (2) promastigote, (3) epimastigote, (4) trypomastigote, (5) opisthomastigote, and (6) choanomastigote. The promastigote stage is that in which the trypanosomatids possess a flagellar locomotory structure that is located anterior of the nucleus and is free from the cell body. It is therefore the flagellate stage of trypanosomatid protozoans.
The promastigote stage is formerly called the leptomonad (stage). However, since the latter term causes confusion with the species belonging to the genus Leptomonas the term promastigote is preferred. The reason for being called a leptomonad stage because this form is commonly found in the genus Leptomonas. The promastigote term is derived from the Greek word mastig which means whip referring to the flagellum).