Ultrastructure of the Endolimax nana cyst

This is the first report on the ultrastructure of the Endolimax nana cyst. These cysts are mostly ovoid in shape and have a distinct cyst wall measuri ng 80 nm. The nuclear membrane is without pores or associated chromatin dep osits. The cytoplasm does not have mitochondria or a Golgi apparatus but sh ows elongated tubular structures made up of a double row of ribosome-like p articles. The nature and function of this structure is not known, but it ap pears to be characteristic of this species and has not been reported from a ny other intestinal ameba.