Fig. 1. (A) Electron micrograph of a section through a mammalian centriole showing the typical nine triplet organisation of microtubules (A, B and C tubules).

(B) Electron micrograph of a longitudinal section through a trypanosome cell, showing the basal body subtending the flagellum. Basal bodies at the base of flagella (and cilia) are structurally similar to centrioles and display a ninefold symmetry. Also visible beneath the basal body is the kinetoplast, an organelle containing the mitochondrial genome of trypanosomes, which is linked to the basal body by a series of filaments (reviewed by Gull, 1999). Scale bars are indicated on each figure.

Abbreviations: f, flagellum; bb, basal body; k, kinetoplast; m, mitochondrion.