TABLE 1.

CLASSIFICATION OF CILIA

Category	Microtubule Arrangement	Cilia per Cell	Motility	Function	Cell Types
Motile cilia	9+2	Multiple	Planar motion	Mechanical; possible secondary chemosensory functions	Airways, spermatozoa, fallopian tubes, choroid plexus, and brain ventricles
Primary cilia	9+0	One	Rotary motion	Mechanosensory; chemosensory	Embryonic node
Primary or sensory cilia	9+0	One	Nonmotile	Mechanosensory; chemosensory	Renal tubules, pancreatic or bile ducts, bone and cartilage, retina, cochlea, developing heart, fibroblasts, etc.