Which organism is characterized by an uninuclear trophozoite?

Which organism is characterized by an uninuclear trophozoite?

• A. Chilomastix mesnil
• B. Balantidium coli
• C. Dientamoeba fragilis
• D. Giardia duodenalis

Answer: (A)

Understanding how many nuclei a trophozoite has helps distinguish these parasites under the microscope. Chilomastix mesnili has a trophozoite with a single nucleus, which is a defining feature of this organism. In practice, this uninuclear form sets it apart from the others listed: Giardia duodenalis trophozoites are characteristically binucleate, Balantidium coli trophozoites show a ciliate with a prominent macronucleus (and micronucleus in ciliates), and Dientamoeba fragilis trophozoites are typically described as having more than one nucleus. So the presence of one nucleus in the trophozoite point directly to Chilomastix mesnili.

Understanding how many nuclei a trophozoite has helps distinguish these parasites under the microscope. Chilomastix mesnili has a trophozoite with a single nucleus, which is a defining feature of this organism. In practice, this uninuclear form sets it apart from the others listed: Giardia duodenalis trophozoites are characteristically binucleate, Balantidium coli trophozoites show a ciliate with a prominent macronucleus (and micronucleus in ciliates), and Dientamoeba fragilis trophozoites are typically described as having more than one nucleus. So the presence of one nucleus in the trophozoite point directly to Chilomastix mesnili.