NeuroFIG 36: Cells of the outer labial sensilla.

A. Schematic rendition depicting the cells of the left-side outer labial sensillar cells. The axons of the neurons are omitted. Four OLQ neurons have ciliated dendritic endings in the dorsal and ventral outer labial sensilla. Two OLL neurons have ciliated endings in the lateral outer labial sensilla. OLQ cell bodies are anterior to the NR, and OLL cell bodies are on the posterior sides of the anterior bulb of the pharynx. All have anteriorly directed dendrites that run in labial process bundles. Posteriorly directed axons from all six neurons rejoin the labial process bundles before they enter the NR and make synapses (not shown).
B. Epifluorescent image of the OLL neuron pair from a transgenic animal expressing the reporter gene ser2prom3::GFP. (Arrow) Midline region in the NR where the dorsal branches of the OLL axons terminate by making GJs to one another; (arrowheads) dendrites of OLL neurons. Dorsal view. Magnification, 400x. (Strain source: O. Hobert.)
C. (Top panel) Epifluorescent image of the bipolar OLLL neuron from a transgenic animal expressing the same reporter gene as in B, lateral view. Seen is the bifurcation of the OLLL axon in the NR (arrow). Both the ventral and dorsal branches make GJs to their symmetrical partners at the ventral and dorsal midlines of the NR. (Bottom panel) Same epifluorescent image is transposed over the DIC image of the head.
D–F. Outer and inner labial socket cells. Epifluorescent images from transgenic animals expressing the reporter gene ITXp::GFP. Most of the OL and IL socket cell somata are grouped around the anterior region of the anterior bulb of the pharynx. The anteriorly directed sensillar processes terminate symmetrically in bulb-like endings within the six lips (arrowheads). Magnification, 400x. D. Left lateral oblique view, medial level. E. Left lateral oblique view, same animal as in D, lateral level. F. Dorsal view. (Strain source: L. Haklai-Topper and E. Peles.)

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