Figure legend

FIGURE 5 Longitudinal and transverse sections of the flagellum and basal body of Naegleria, illustrating the proximodistal structural differentiation of the basal body. Fig. 5 a, longitudinal section; Fig. 5 b, typical flagellum axoneme; Fig. 5 c, flagellum at the level of the basal plate; Fig. 5 d, transitional region between flagellum and basal body; Fig. 5 e, typical basal body structure; Fig. 5 f, proximal basal body, showing the single central filament, spokes, and triangular condensations within the cylinder of triplets. All micrographs, approximately x97,000.

Figure notes

More information about the transition zone: "Distally, at the transitional zone between flagellum and basal body, a thin membrane lying just within the cylinder of peripheral doublets circumscribes the 2 central filaments (Fig. 5 c)." The referred membrane is very similar to concentric fibers find in other articles. Slightly beneath this level, these or similar fibers become elongate and diffuse, creating a pinwheel effect in the cytoplasm surrounding the basal bodies (Fig. 5 d). The central filaments terminate at or before this point; in the center of the cylinder is a diffuse area of intermediate electron-opacity, which is presumably the basal granule or basal plate. The axial filament complex is intermediate in structure between that of the flagellum and that of the median basal body at this level; some of the peripheral filaments are doubled and others are tripled." The basal plate is very similar to the axosomal plate reported in other organisms like Paramecium. The authors refer connecting fibers in the rhizoplast-basal body junction. The transition zone also seems to have the structures called "pegs", found in other organisms. The fibers mentioned in the transition region seem similar to the transitional fibers also found in other organisms. More information found in the text: "The basal body varies from 0.7 to 2.0 um in length; transverse sections measure approximately 0.2 u in diameter, but the basal body tapers gently from 0.24 um proximally to 0.21 um distally, merging ultimately with the 0.18 um diameter axoneme." Flagella: "measure from 7 to 17 um in length and 0.3 to 0.5 um in diameter."