Fig. 2

Ultrastructure of BBs and associated structures in S. mediterranea. Transmission electron microscope views of BBs in (a, c, d) sensory neurons and (b) epidermal MCCs. a Longitudinal view of a BB in an epidermal process emanating from a subepidermal sensory neuron. TZ transition zone, arrow ciliary rootlet. b Transverse view of a BB showing the basal foot (arrowhead) and the horizontal ciliary rootlet (arrow). c Transverse view of a BB in a sensory process showing nine-fold symmetrical blade-like structures. d Transverse section through the same BB as in (c) 100 nm away toward the distal end showing the distal appendages (also called transition fibers). Solid lines are used to highlight the distal appendages, dotted lines are used when the distal appendages are not clearly visible on this section. Bar is 0.2 µm in (a–d)