Anal pore
The anal pore or cytoproct is a structure in various single-celled eukaryotes where waste is ejected after the nutrients from food have been absorbed into the cytoplasm.
In ciliates, the anal pore and cytostome are the only regions of the pellicle that are not covered by ridges, cilia or rigid covering. They serve as analogues of, respectively, the anus and mouth of multicellular organisms. The cytopyge's thin membrane allows vacuoles to be merged into the cell wall and emptied.
