SeamFIG 3: Seam cells make special cuticular structures called alae in L1, dauer and adult stages.

The seam cell in each TEM panel is marked by an orange line. Bars, 1 μm.
A. TEM, transverse section from the head of an L1-stage animal. (Amp.) Amphid nerve. (Image source: [MRC] L1C 48, right side.)
B. TEM, transverse section from the body of an L2-stage animal. There is no ala in the cuticle overlying the seam. (N) Seam nucleus. (Image source: [MRC] N2SE1 L2 179, right side.)
C. TEM, transverse section from the body of an L4 animal. There is no ala in the cuticle overlying the seam. (N) Seam nucleus. (Image source: [MRC] JSH 165 L4, right side.)
D. TEM, transverse section from the body of an adult-stage animal. Trilaminated adult alae are present over the seam. (Image source: [Hall] N501A Q’5 1255.)
E. TEM, transverse section from an adult animal at midbody level. Vulval and uterine cells and uterine muscles (um1L/R) are anchored to the lateral seam in this region. (Image source: [MRC] N2 vulva 28.)
F. TEM, transverse section from an adult animal at the level of the phasmids. Seam syncytium is about to end and alae have become a single bump in the cuticle. (Image source: [Hall] B140 C5 480.)
G. TEM, transverse section from the head of a dauer-stage animal. Dauer-specific alae overlay the seam. (Image source: [Riddle] 50 2 1 710.)
H & I. SEM of an adult animal showing the head (H) and tail (I) regions. The trilaminated structure of alae converges into a single ridge over the anterior and posterior (white arrows) ends of the seam.
J. DIC image of a wild type adult animal showing the three ridges of the alae. Original magnification, 600x.
K. Overlay of DIC and epifluorescence images of a transgenic adult animal expressing the F09D12.15::GFP reporter in the seam. Alae are in register with the seam. Original magnification, 600x. (Strain source: The Genome BC C. elegans gene expression consortium; McKay et al, 2004.)

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