Morphological Analysis of Leishmania major

Gut smears of L. major-infected females 5, 9 and 12 days PBM were fixed with methanol, stained with Giemsa and examined under the light microscope with an oil-immersion objective. One hundred and sixty randomly selected promastigotes from four sand flies/smears were measured in each combination of Leishmania line and time PBM. Body length, flagellar length and body width of parasites were measured and position of the kinetoplast in relation to the nucleus was examined. Four morphological forms were distinguished, based on the criteria of Walters (1993) (link) and Cihakova and Volf (1997) (link): (i) short promastigotes: body length < 14 µm and flagellar length < 2 times body length; (ii) elongated nectomonads: body length ≥ 14 µm; (iii) metacyclic promastigotes: body length < 14 µm and flagellar length ≥ 2 times body length, and (iv) round forms: body width > 4 µm and body length ≤ 7.5 µm include also paramastigotes with kinetoplast lateral to the nucleus. We use here the term short promastigotes derived from the terminology of Walters (1993) (link) (short nectomonad promastigotes) which is the older synonym of leptomonads (leptomonad promastigotes) proposed by Rogers et al. (2002) (link). Haptomonads cannot be distinguished in this study as they remain attached to the gut and cannot be measured on gut smears.