Figure 2
Bbs1M390R/M390Rmouse ependymal cilia exhibit structural abnormalities as early as P9. Neutral red-stained coronal sections of P9 wild-type (A, C) and Bbs1M390R/M390R mice (B, D) illustrate the early appearance of lateral ventricle enlargement while the 3rd ventricle has not yet enlarged. TEM micrographs of P9 wild –type (E) and mutant (F, G) Bbs1M390R/M390R ependymal cilia, 3.5 week-old (H) and 7 month-old (I-K) Bbs1M390R/M390R cilia show typical IFT-like particles (arrows) and atypical vesicle-like inclusions and electron dense material (arrowheads) in cross-section and in longitudinal sections. The foreign material appears just distal to the transition zone (F) or between the axoneme and the ciliary membrane (F, G). In some extreme cases, the axoneme appears to be disrupted with bloating of the cilia beyond the transition zone (H-J). Disruption of the 9 + 2 axoneme is seen in cross-section in addition to the presence of electron-dense material (K). Note the broken radial spokes that link the peripheral microtubule doublets to the central pair and the broken nexin links between the peripheral microtubule doublets (K). TZ (transition zone), IFT-like particles are noted by arrowheads. Arrows point to axonemes (G). Bars equal 1 mm (A-D), 0.5 μm (E-K).