G. lamblia has two morphological stages: the trophozoite and the cyst.
- The trophozoite is pear shaped, with a broad anterior and much attenuated posterior (9). It is 10-12µm long and 5-7µm wide, bilaterally symmetrical, and has two nuclei.(9) It is also relatively flattened, with a large sucking disk on the anterior ventral side, which serves as the parasite’s method of attachment to the mucosa of the host. The trophozoite also has two median bodies and four pairs of flagella (anterior, caudal, posterior and ventral) (1).
- The G. lamblia cyst is egg-shaped, and measures 8-14µm by 7-10µm. (9) After encystation, each organelle duplicates, so each cyst contains four nuclei, four median bodies, eight pairs of flagella--although these organelles are not arraigned in any clear pattern. (9) Upon excystation, each cyst produces two trophozoites. (9)