Primary 9 + 0 cilia in the embryonic and the adult human heart.

Primary 9 + 0 cilia have been found in the embryonic and the adult human heart. Proximally the cilia show the typical 9 + 0 filament arrangement. Rearrangement of the filaments occur in their distal regions. The cilia are usually found in deep invaginations of the cell membrane, but can also be found in a superficial position. Close connections are frequently found between cilia and thin cytoplasmic extensions from neighbouring cells.