Answer to Case 729

 Answer to theParasite Case of the Week 729: Trophozoites of Chilomastix mesniliBelow is an answer written by Dr. Jacob Rattin (@EternalStudying):This non-pathogenic flagellate has pear-shaped trophozoites that are 6 – 24 μm long with a longitudinal spiral groove running along the body (not seen in this specimen). If visualized in a fresh prep, the motility may allow the spiral groove to be seen as the organism turns (seeCase 475). The trophozoite has one nucleus (arrowhead), usually at the anterior end, with an eccentric karyosome and a cytostome (oral groove) close by.  The posterior end tapers to a point (arrow). DifferentiatingC. mesnilitrophozoites from other non-pathogenic flagellates such asEnteromonas hominis,Pentatrichomonas hominis, andRetortamonas intestinaliscan be quite difficult. Thankfully, these organisms are non-pathogenic. However, the following features may be useful in teasing apart these fun flagellates!Enteromonas hoministrophozoites measure 5 – 7 µm long with one nucleus and three anterior flagella and one posterior flagellum. It has a single nucleus with a large karyosome. There is no cytostome which helps to differentiate it fromC. mesnili. Retortamonas intestinalisare 4 – 10 µm long with an ovoid trophozoite form with a cytostome at the anterior half that is bordered by a fibril. The single nucleus is at the anterior end and has a small karyosome.Pentatrichomonas hominis. The trophozoites are pyriform in shape, measu...
Source: Creepy Dreadful Wonderful Parasites - Category: Parasitology Source Type: blogs