Atypical cilia in the choroid plexus of guineapig.

Ultrastructural study of choroid plexus of normal and kaolin induced hydrocephalic guineapigs showed clusters of cilia arising from the apical part of some of the epithelial cells. Some of these cells had typical 9 + 2 cilia, while most of the control and the hydrocephalic groups showed 9 + 0 type of cilia. These atypical (9 + 0 type) cilia of choroidal epithelium differ from the primary cilia of other mammalian tissues in that, clusters of long cilia arise from a single cell and have no associated centrioles within the cytoplasm. They may be motile and sensory (osmoregulator or pressure sensor or both) in nature.