Fig. 4. Aberrant organization of early embryonic dorsal hypodermal and seam cell precursors and the resulting differentiated cells in unc-62 mutant embryos. Scale bars represent 10 µm. (A-D) Nomarski images of embryos (dorsal or ventral view, dorsal focal plane, anterior leftwards) that were lineaged to identify cells and photographed about 4 hours post-fertilization (22-25°C). Precursors of hypodermal cells derived from the C lineage and seam cells derived from V lineages are positioned as indicated. (A) Wild-type embryo. Note that dorsal C-derived hypodermal precursors are flanked by V-lineage cells. (Although this embryo is shown approximately one division earlier than the other embryos, the relative position of dorsal midline C hypodermal cells and lateral V precursors is already established at this time, and does not change.) (B) s472 mutant embryo. Some of the C hypodermal precursors lie abnormally ventral to this focal plane, and are not visible. (C) t2012 mutant embryo. (D) ct344 mutant embryo. Embryos in B-D are about one division later than the embryo in A. Relative positions of the C- and V-derived hypodermal cells are aberrant in the three mutants. (E-N) Nomarski and fluorescent images (lateral views, surface focal plane, anterior leftwards) of embryos and larvae expressing JAM-1::GFP, a marker for hypodermal cell junctions. (E,F) Wild-type newly hatched L1, showing the normal expression of JAM-1 at the borders of the row of seam cells. The dorsal and ventral hypodermal cells have fused into syncytia, showing no cell boundaries. (G,H) s472 newly hatched L1. There are few outlined cells, which do not show a contiguous seam cell pattern. (I,J) e644 L1, with a more normal pattern but some dorsal hypodermal cells that have not fused. (K,L) t2012 newly hatched L1, with disconnected seam cells. (M,N) ct344 late embryo, with few, abnormally large seam cells.

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