Fig. 5. Morphological defect in hyp4 of smp-1 mutant animals results in a displaced mouth phenotype. DIC microscopy reveals a mouth displaced to the ventral side in the mutant (B, arrow) compared with the wild type (A, arrow). (C,D) jam-1::gfp is used to visualize adherens junctions between hypodermal cells. Arrows indicate buccal opening (mouth). (E,F) Analysis of contacts between the mutant (F) and wild-type (E) head epidermal cells are summarized. Instead of forming a cylindrical shaped hyp 4 cell and cylindrical head as in the wild type (A,C,E), in smp-1 (ev715) (B,D,F) hyp 4 forms an abnormal contact with itself (failure to fuse) and probably with hyp 3 and hyp 5 that results in torrid-shaped cells that are thinner on the ventral side. The oddly shaped hyp 4 presumably causes tilting of the pharynx toward the ventral side and consequent formation of a displaced mouth.