Figure 1.

Selected tomographic slices from the proximal to distal (A–F, respectively) region of a wild-type basal body complex. (A) One basal body is shown in cross section (BB1) and the other basal body in longitudinal view (BB2). The proximal base of BB1 consists of an amorphous, electron-dense ring and there is a ninefold symmetric pinwheel structure in its center (arrow). A two-membered rootlet microtubule bundle is seen (rMT). (B) The pinwheel structure of BB1 has a center formed from three rings (arrow). Other obvious features include the membrane compartments of the CV and the ordered arrangement of the striated fiber associated with the rootlet microtubule bundle (rMTf). (C) Two probasal bodies (proBB1 and proBB2) lie adjacent to the mature basal bodies. Other features include a four-membered rMT bundle as well as a fiber connecting BB2 to this rootlet bundle (arrow). (D and E) The dsf and rMTs are indicated. (F) Transitional fibers (f) radiate out from the triplets at the distal end of the basal body. Video sequence 1 shows a movie of 216 serial tomographic slices through this volume. Bar, 100 nm.