ExcFIG 6: Development of the canals.
TEM of transverse section from an embryo at ~400-430 minutes showing tubular arms growing into rudimentary canals. The canals are about to reach the lateral hypodermal ridges on the right and left sides. An electron dense material (arrowheads) appears within the lumens. (Inset) An earlier stage animal with two vacuoles within the cell body. (N) Nucleus; (No) nucleolus. Bar 1 Ám. (Image source: [MRC-R. Durbin] RDB [inset: RDA].)
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