Figure 3. NC-6 expression in the embryonic ectoderm and proposed guidance functions.

Figure 3

NC-6 expression in the embryonic ectoderm and proposed guidance functions. (Top) The AVG (red) axon runs posteriorly along the ventral midline. The body wall is shown opened along the dorsal midline in cylindrical projection, and the nerve ring is flattened in anterior projection (cf. White et al. 1986). Excepting neuron I5 in the pharynx, all cells that express UNC-6 in the embryo are shown. Stars mark additional cells, included for reference, that do not express UNC-6. Neurons are located within various ganglia, i.e., lateral (AVA, AVB), retrovesicular (AVG, RIF), preanal (PVP, PVT), or lumbar (PVQ). The excretory pore (middle) and anus (right) provide landmarks along the ventral midline. Cephalic sheaths (CEPsh) support RME and other axons within the ring neuropil. Inner labial sheaths (ILsh) may guide axons entering the neuropil from the anterior via the six labial nerves. Cephalic sheaths may guide axons entering the neuropil from the posterior via lateral (e.g., AVA) and ventral routes (e.g., AVB). AVA and AVB axons undergo reciprocal decussations at the dorsal midline of the ring. Ventral hypodermoblasts (epidermoblasts P1/2-P11/12) are represented by the six subdivisions shown on the body wall. These hypodermoblasts support axons within the ventral nerve cord. Guidepost neurons AVG and PVT may mark the anterior and posterior boundaries of the nerve cord proper. (Lower left) The body wall and nerve ring are shown in cross section through the head. The ventral cephalic sheaths, which express UNC-6, are filled. Axons of neurons AVA and AVB in the lateral ganglia enter the nerve ring by lateral and ventral routes, respectively. (Lower right) The body wall is shown in cross section through the midbody. The ventral hypodermoblasts, which express UNC-6, are filled. Typical sensory and motor neurons are shown projecting to the ventral and dorsal nerve cords, respectively. (Reprinted, with permission, from Wadsworth et al. 1996, copyright by Cell Press.)

From: Section II, Neuroglia and Pioneers

Cover of C. elegans II
C. elegans II. 2nd edition.
Riddle DL, Blumenthal T, Meyer BJ, et al., editors.
Cold Spring Harbor (NY): Cold Spring Harbor Laboratory Press; 1997.
Copyright © 1997, Cold Spring Harbor Laboratory Press.

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