NeuroFIG 13: Head commissures.

Many laterally positioned head neurons send processes to the VNC via four head commissures: two amphid and two deirid.
A. Graphic rendition showing only the left-side commissures. Amphid commissures are situated on the left and right sides, immediately anteriorly to the terminal bulb of the pharynx. They are mostly comprised of the axons of the amphid neurons. Deirid commissures allow axons from the neurons situated on the lateral sides of the posterior pharynx to enter the VNC. The majority of the fibers in these commissures travel to the NR. (Ep) Excretory pore.
B. Epifluorescent image from an animal expressing the reporter gene str-2::GFP in AWCL. Each AWC axon travels via the amphid commissure (arrowhead), left lateral view. The pharynx is outlined in green. Magnification, 600x. (Strain source: C. Bargmann.)
C. Epifluorescent image from an animal expressing the reporter gene dat-1::GFP in ADE neurons, left lateral view. The ADEL axon travels posteriorly to enter the left deirid commissure (arrowhead) and then anteriorly into the ventral ganglion. The pharynx is outlined in green. Magnification, 600x. (Strain source: S. Clark.)

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