Fig. 5. Analysis of cilia in the ventricular system in 1-day-old mice. Brain sections of a 1-day-old wild-type mouse containing the (A) lateral and (B) third ventricles, (C) the aqueduct and (D) the fourth ventricle were analyzed for the presence of cilia (anti-acetylated-tubulin, green; polaris, red) on the ependyma (white arrowheads) and the choroid plexus epithelia (white arrow). No multi-ciliated cells were evident on the ependyma of the (A) lateral, (B) third or (D) fourth ventricles at this age. Ependymal cells possess primary cilium, as shown by the SEM and immunofluorescence (inset in A,E; yellow arrowheads). (C) By contrast, the ependymal lining of the aqueduct was multi-ciliated (white arrowhead). Inset shows that multiple cilia are also present in the mutant aqueduct. (F) Multiple cilia cover cells in the aqueduct (yellow arrowheads). (G) Grouped and single cilia on the choroid plexus. Scale bars: in A-D, 200 µm; in E-G, 10 µm.