Figure 1.

Subtypes and anatomy of Caenorhabditis elegans glia. (A) A schematic representation of each glia type in the head, (A′) hermaphrodite tail, (A′′) and male tail. Anterior and posterior deirid glia (ADEsh/so, PDEsh/so) are not depicted. Glia–neuron associations are magnified in B–E as follows: amphid glia (B), IL socket glia (C ), cephalic sensilla (E), and cephalic posterior membrane sheaths enveloping the brain neuropil (D). (B–B′): (B) Amphid sensilla schematic showing AMso–AMsh sense organ glia forming a channel lumen associating with dendrite tips, neuron-receptive endings (NREs) that traverse the glial channel (ASE, ASH, ADL), and embedded NREs (AFD and AWA/B/C neurons). (B′) Cross section of bilateral AMsh glia–AWC pairs, (C ) ILso glia interact with NREs of different neurons (URX, IL, BAG) at distinct contact sites, with only IL neurons traversing a channel made by the glia. (D) Schematic of CEPsh glial processes (green) ensheathing different axon commissures. (D′) A schematic cross-section view of the brain neuropil shows the relative location of axon commissures with CEPsh and GLR glia. (D′′) Glial processes also infiltrate between neuron processes in the neuropil. (D′′′) Electron micrograph showing the CEPsh glia–ALA neuron–AVE neuron tripartite synapse. (E) Schematic of the cephalic sensilla of a male animal, noting relative localization and glia–neuron contacts of the sex-shared CEP neuron and male-specific CEM neuron. Sensory NREs in B, C, and E are depicted without dendrites and cell bodies for simplicity. Neurons in D are depicted without dendrites for simplicity. (Schematics in A, B, and D are reprinted from Singhvi and Shaham 2019 with permission from the author. Electron microscope [EM] image in D′′′ is adapted with permission from White et al. 1986. Schematic in C is based on data in White et al. 1986, Ward et al. 1975, and Cebul et al. 2020. Panel E is based on data in Wang et al. 2015 and Sulston et al. 1980.)