Fig. 2. Defective sensory cilia in unc mutants. (A-F) Sensory neurons in the antenna (A-D) and the femoral chordotonal organ (E,F), labeled by neuronal expression of mCD8-GFP. Arrows indicate ciliary outer dendritic segments, and arrowheads to the tips of the inner dendritic segments. In wild type, cilia extend from sensory processes of olfactory neurons on the antenna (A, enlarged in B) and femoral chordotonal neurons (E). In unc mutants (C,D,F) neurons and inner sensory processes are still present, but the cilia are missing or truncated. (G-L) ultrathin sections of individual sensory units (scolopidia) in chordotonal organs. (G) Transverse sections of wild-type scolopidia, showing profiles of two cilia (ci) enclosed in each scolopale (sc). (H,I) unc mutant femoral (H) or antennal (I) scolopidia with missing or disrupted cilia (box and inset). Sections through some basal bodies (I) also showed breaks (inset). (J) Schematic of a scolopidium, relating numbered section planes to the sections seen in G-I. (K,L) Longitudinal sections of wild-type and mutant ciliary bases. Basal bodies appear as paired electron-dense structures (arrowhead); the distal basal body was often less clearly defined in mutant cilia. Scale bars: 20 µm in A,C; 5 µm in E; 1 µm in G; 0.2 µm in K.