SeamFIG 1: Seam is composed of a longitudinal string of cells on each side of C. elegans.
A. Schematic view of left lateral seam cells in an L1-stage larva. At this stage, ten embryonically born individual seam blast cells contact each other through adherens junctions. They are also in close contact with P blast cells on the ventral side.
B. Schematic view of left lateral seam cells in adult hermaphrodite. Seam cells have increased in number to 16 on each side through post-embryonic seam divisions. At L4/adult molt, seam cells fuse to one another making one longitudinal syncytium on each side of the adult animal that extends between the hyp 5 and hyp 7 junction at the anterior and the phasmids at the posterior.
C. Schematic view of seam cells embedded in the hypodermis, looking from the inside out. Except for the most anterior seam cells, each seam cell has a smoothly tapered oval shape. After mid-L1, all seam cells become embedded within the major hypodermis, hyp 7. The apical face of each seam cell faces the cuticle and remains in contact with the cuticle along the full length of the cell (a, b). At their largest cross section, seam cells come into contact with pseudocoelom through holes in hyp 7 (a). (Gray) Cuticle (c); (beige) hypodermis (h); (orange) seam (s); (yellow) pseudocoelom (p); (bl) basal lamina.
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