Third ventricle suprachoroidal cells.

Using transmission electron microscopy two types of cells on the choroid plexus of the third ventricle of the frog Rana esculenta have been located. They lie on the microvilli and cilia of the choroid epithelium. Their free surface is in contact with the cerebrospinal fluid. One type, Kolmer-like, has large, dense bodies in its cytoplasm. The cytoplasm of the other type is completely filled by large, ovoidal structures which have a limiting membrane and a polymorphic filamentous content. Their functional significance is unknown.