miracidium of Megalodiscus temperatus from Rana pipiens.
This section includes a cross section through one of the two flame cells.
The circular bodies are cilia which fuse into a cone of cilia. They
rhythmically undulate, forcing fluids down the excretory ducts toward the
bladder for elimination. The open space to the lower right is an excretory
duct, revealing the presence of sparse microvilli. The black material is
glycogen. 35,000x