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[Leishmania spp.]

Amastigotes of Leishmania are spherical to ovoid and measure 1-5 µm long by 1-2 µm wide.  They possess a large nucleus, a prominent kinetoplast, and a short axoneme, the last of which is rarely visible by light microscopy.  The organisms reside in macrophages of the host and can be found throughout the body.

A

A:  Amastigotes of Leishmania sp. in a biopsy specimen from a skin lesion, stained with hematoxylin and eosin (H&E).

B

B:  Leishmania mexicana in a biopsy specimen from a skin lesion stained with H&E.  The amastigotes are lining the walls of two vacuoles, a typical arrangement.  The species identification was derived from culture followed by isoenzyme analysis.