NeuroFIG 1: The C. elegans nervous system.

A. Epifluorescent image of a transgenic animal expressing a panneural reporter, left lateral view. The largest collection of neurons is around the nerve ring (NR) within several head ganglia, including the retrovesicular ganglion (RVG) and ventral ganglion (VG; also, inset). The second largest collection of cell bodies is in the tail ganglia (the left lumbar ganglion and preanal ganglion are shown). A few single neurons, including ALM, CAN, or small groups of neurons (lateral ganglia), are also found along the lateral body wall. Longitudinal nerve tracts travel along the body at ventral, subventral, lateral, subdorsal, and dorsal positions and connect cell bodies to major neuropils. Anterior to the ring, several sensillar nerves reach the tip of the head. VNC (ventral nerve cord) motor neurons are scattered along the VNC and send processes to the DC via commissures (arrowheads). The pharyngeal nervous system is an autonomous network of 20 pharyngeal neurons (NSML, which is situated within the anterior bulb, inset). Note that this reporter is also expressed in head muscle cells (arrows, inset). Magnification, 400x. Strain marker: unc119::GFP. (Strain source: CGC.)
B–D. Differential interference contrast (DIC) images of the head of a young adult animal at three planes, viewed from the left side.
B. On the lateral side are left-side lateral ganglion nuclei posterior to the NR.
C. At a more medial level, more NR fibers are seen extending from the VNC and growing around the isthmus (black circle). Neurons of the dorsal ganglion (neuron nuclei) become visible at this level.
D. At a slightly more medial level, multiple labial neuron and support cell nuclei become visible anterior to the NR around the anterior bulb, whereas more lateral ganglion nuclei are visible posterior to the NR. Magnification, 600x.

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