Trophozoites of Trichomonas vaginalis measure 7 to 30 micrometers in greatest dimension and have a round/oval to piriform (pear) shape. They have a characteristic large nucleus (usually found at the broader end) and flagella. They have 4 anteriorly directed flagella and one posterior-facing flagellum that lies along the outer edge of the undulating membrane. The first 2 images below show several Giemsa-stained trophozoites from in vitro culture (1000x magnification). The other images are taken from Papanicolaou-stained conventional cervical smears. You can see that the morphologic features are less defined with this method.