FIGURE 8.

Neurons can be identified from 3D volumes. Electron micrographs showing snapshots of part of the ventral nerve cord from an animal at the end of the second larval stage, imaged using SEM at 2 nm/pixel. (A) A VD2 NMJ is pointing laterally toward a muscle arm. This example also “hits” a projection from the VA2 motor neuron, but it is not clear if receptors are present. Some other motor neurons are also labeled, to give a sense of the relative position within the nerve cord. (B) A VA2 NMJ is pointing more dorsally, releasing onto a muscle arm, a DD1 spine and VD2. (C) A VB2 NMJ is also pointed dorsally, releasing onto muscle, a DD1 spine and VD2. (D) A cartoon of most of the commissure bundles in C. elegans, available on WormAtlas (Altun et al., 2002–2018) and based on The Mind of a Worm (White et al., 1986). The positions, handedness and commissure bundle partners are known, and very stereotypic. Bundles of neuron processes are shown as red cables. The cell bodies are denoted with spheres, and also have stereotypic positions along the body of the worm and relative to each other.