Figure 2.

Divergence in length and position of cartwheel stacks (shown in red). (a) Dynamic change in the Chlamydomonas cartwheel stack during the centriole duplication cycle [18]. As the cell cycle progresses (from left to right), the lengths of the stack and microtubules change. (b) The cartwheel stack in Spermatozopsis also changes in length during the cell cycle. The cartwheel stack protrudes from the centriole lumen and apparently serves as a microtubule-organizing centre [16]. (c) In mammals, a cartwheel stack exists in the procentriole (left), but disappears from a fully assembled centriole (right). (d) The Trichonympha centriole is approximately 4 μm long, while the canonical centriole is approximately 0.4 μm long. The lumen except for the distal 10% is filled with cartwheels. Thin and thick blue lines indicate triplet and singlet microtubules, respectively. (Online version in colour.)