List of abbreviations
of micros-
specialist terms
explained in
English +

Every attempt was made to provide correct information and labelling, however any liability for eventual errors or incompleteness is rejected!

dieser Seite

Dr. med.
H. Jastrow

of use
Overview Kinocilia (Kinocilia):
Pages with explanations (in German) are linked to the text below the images if available
basal body (rat)
Kinocilia with
basal bodies 1 (monkey)
Kinocilia with
basal bodies 2 (monkey)
Kinocilia with
basal bodies 3 (monkey)
Basal bodies of kinocilia
and root fibres (monkey)
Kinocilia of the
fallopian tube (rat)
Microvilli + Kinocilia
(Trachea, monkey)
Microvilli + Kinocilia
(Trachea, monkey) 2
Kinocilia and
microvilli lengthwise (monkey)
kinocilium - basal body border
stereo image (rat)
Kinocilia + micro-
villi cross sectioned (rat)
respiratory epithelium 1
 pharyngeal tonsil (human)
respiratory epithelium 2
+ goblet cell (human)
respiratory epithelium 3
 pharyngeal tonsil (human)
idem 4 cross-section
 pharyngeal tonsil (human)
Detail thereof
 pharyngeal tonsil (human)
End of a Kinocilium
 pharyngeal tonsil (human)
cross-sectioned basal bodies
pharyngeal tonsil (human)
 idem pharyngeal
tonsil (human)
Trachea: epithelium
with kinocilia (monkey)
Kinocilia or just cilia (Terminologia histologica: Kinocilia) are parallel oriented, motile, finger-like protrusions of cell membranes connected to a basal body.
The diameter of the cilia and basal bodies is about 300 nm, length of cilia 7 - 10 µm, length of basal bodies ~ 0.5 µm.
As a characteristic, cilia possess a central pair of microtubules sourrounded by an inner sheath. Nine outer pairs of microtubules are connected to the central pair by radial spokes which extend at right angles onto them. The 9 outer pairs of microtubules are connected to each other by nexin bridges. All ciliary microtubules run parallel to each other. In cross sections their specific 9x2+2 structure is well defined.
While the central tube-like microtubules are similar in constitution to those of the cytoskeleton (13 tubulin dimers) the 9 outer pairs consist of tubular A-tubuli (13 tubulin dimers) to which c-shaped B-tubuli (10 tubulin dimers) are attached. This connection is fortified by 48 nm long, 2 nm thick filaments of the alpha-helical protein tectin. The total of filaments inside the cilia is called axonema. It contains some proteinaceous connections: The central pair of microtubules is interlinked by bridging proteins and a fibrous inner sheath. Nexins are encountered every 86 nm along the axonema. They connect an A-tubulus to the B-tubulus of the adjacent pair. These bridges break during ciliar motion and re-establish in higher or lower position using ATP when the doublet microtubules slide by each other. This sliding is caused by ATP consuming movement of dynein molecules. The latter are attached to the A-tubules in form of an outer and an inner arm reaching towards the B-tubules of the adjacent pair. Thus the tubules slide by each other like muscle filaments.
The outer doublet microtubules of the cilia continue into those of the basal bodies at the level of the cell membrane in a manner that another c-shaped tubule (10 tubulin dimers) is added to the B-tubule. The central pair of microtubules ends here and the inner sheath continues in a ring-like proteinaceous structure that disappears at the distal region of the basal body. There are 9 microtubular organization centres (MTOCs) attached to the sides of the basal bodies. The basal bodies serve for regeneration of the tubular material but not for movement of the cilia. At the base these proteinaceous formations end in rootlet fibres that reach far down into the cytoplasm where they are anchored on the cytoskeleton. These rootlets and the connections to the MTOCs at the sides of the basal bodies show a periodic striping and contain the protein centrin.
Kinocilia are typical for the respiratory epithelium present in nose, paranasal sinuses, larynx, trachea and bronchies. Pollen and debris is transported here towards the throught by the well coordinated beating of the cilia which has a frequency of about 8-12 Hz. Movement is a quick protrusion followed by a slower pulling back of the cilia which is organ specific and genetically determined. The metachron action of the cilia causes an oriented flow of secretions on the surface of all epithelia showing kinocilia. The density of these cell surface specialisations is demonstrated, e.g. in the oviduct with about 10,000,000 cilia present in 1 mm² of its surface.
Flagellae are single, very long cilia serving for movement of free cells. They are encountered, e.g. in the tails of sperms which are about 55 µm in length.
The term cila as such is used for the reduced cilia of rods and cones in retina which are not mobile but needed as stable structures to fix the large outer segment of the photoreceptors to the cell body. They only have  9 x 2 + 0 microtubules, i.e. the central pair is missing.

--> Flagellae, microvilli, cell surface structures
--> Electron microscopic atlas Overview
--> Homepage of the workshop

Some pictures were kindly provided by Prof. H. Wartenberg, further images, page & copyright H. Jastrow.