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CIL:11558*  Cite 

Figs. 303 & 304 from Don Fawcett's Chapter 12 (Centrioles). In transverse section the cylindrical wall of the centriole is made up of nine longitudinally oriented triplet microtubules. A dense material of unknown nature occupies the interstices between the triplets. Each triplet is at a constant angle of about 40 degrees to its respective tangent. A pattern is thus formed that resembles the vanes of a turbine or the charges of a pyrotechnic "pinwheel." The innermost microtubule of each triplet has a circular cross section and is designated subunit a and the other two b and c. The latter two each share a segment of the wall of the adjacent microtubule and therefore have a C-shaped profile instead of a circular cross section. Subunit a has two short diverging projections resembling the arms on the doublets of the ciliary axoneme. One of these is directed inward along a radius and appears to have a free end pointing toward the center of the centriole. The other projection connects with subunit c of the next triplet. The successive triplets are thus linked together a to c around the circumference of the centriole by a series of linear densities. It is not known whether these latter correspond to the dynein arms or nexin links of flagellar axonemes. A copy of the chapter is available on the ASCB's BioEDUCATE website.

Biological Sources
NCBI Organism Classification
unknown eukaryote
Cell Type
eukaryotic cell
Cellular Component
Biological Context
Biological Process
centriole organization
Don W. Fawcett
Susumu Ito
Jean Andre
ISBN 0721635849
Digital Object Identifier (DOI)
Archival Resource Key (ARK)
Grouping This image is part of a group.
Image Type
transmission electron microscopy (TEM)
illumination by electrons
Image Mode
detection of electrons
Parameters Imaged
electron density
Source of Contrast
stain with broad specificity
Visualization Methods
stain with broad specificity
osmium tetroxide
uranyl salt
lead salt
Processing History
recorded image
Print from negative scanned for Photoshop.
Data Qualifiers
processed data
Spatial Axis Image Size Pixel Size
X 918px ——
Y 1288px ——