DNeuroFIG 7: Enlargement of dauer anterior deirid sensillar endings.
A & C. Illustration of a dorsal view of the deirid sensillum. Unlike most nematode sensors, the ADE neuron cell body lies peripherally in close association with the sensory apparatus. Each ADE also extends two axons (not shown), one to the nerve ring and one to the ventral nerve cord where ADE makes synapses onto multiple targets (White et al., 1986). In dauers, the electron-dense region inside the tip of the deirid cilium is reoriented in parallel with the main anterior-posterior body axis. In contrast, the nondauer sensillum is tangentially oriented to the main A-P body axis. Bars with letters indicate approximate positions of transverse sections shown in B & D.
B. Transverse TEM section of the anterior deirid sensillum in an L4 larva recovered from the dauer stage. This structure is representative of other non-dauer stages. This image shows the structure of the electron-dense sensillar ending which abuts the cuticle and the cuticular nubbin.
(Image source: N2 L4 55-3-1 [D. Riddle] 162.)
D. Transverse TEM section of the anterior deirid sensillum in a dauer larva. A novel truss-like cuticular structure can be seen locally expanding and reinforcing the basal cuticle layer, surrounding the enlarged deirid ending. This structure may provide structural support for the sensillum, or amplify the zone along the lateral line that can effectively stimulate the deirid ending. An extended electron-dense extracellular nubbin still links the deirid ending to the basal cuticle.
(Image source: N2 starved dauer 50-2-2 [D. Riddle] 996.)
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