||Amastigotes: Eleven amastigotes of Leishmania
donovani in a macrophage. They are formed after the macrophage
phagocytizes an infective promastigote. Each amastigote is about
3 um in length.
||Promastigotes: Promastigotes of Leishmania donovani
(from culture). Promastigotes are characterized by a flagellum and
a kinetoplast (arrow) anterior to the nucleus. They are the infective
stage to humans.
||Promastigotes: Promastigotes of Leishmania tropica
(from culture). Note the multiplication by longitudinal binary fission
(arrow) that occurs naturally in the gut of sandfly vectors.