Fig. 5. Pharyngeal morphogenesis in wild-type and mutant animals. DIC (A,C,E,G,I,K) and corresponding GFP fluorescence (B,D,F,H,J,L) images showing the outline of pharyngeal (and intestinal) cells in wild-type (A-D) and ubc-18; lin-35(RNAi) mutant (E-L) embryos. Anterior is towards the left and ventral is downwards. Black arrows demarcate the anterior pharyngeal boundary. (M) A schematic for pharyngeal extension involving three discrete steps (also see text). (A,B) An early comma-stage embryo, before overt signs of morphogenesis have begun. Note the teardrop shape of the leading-edge epithelial cells (white arrowheads, B). (C,D) 1.5-fold-stage embryo with pharynx now extended to the anterior. Note the transformation in the shape of the leading-edge epithelial cells (white arrows, D). (E,F) 1.5-fold and (G,H) 2-fold-stage mutant embryos where leading edge epithelial cells have failed to reorient (white arrowheads in F,H). (I-L) 1.5-fold-stage mutant embryos in which dorsal epithelial cells have failed to reorient their axes (white arrowheads) whereas ventral cells in the same embryo appear to have undergone the proper transformation (white arrows). (M) Pharyngeal extension with three distinct steps (Portereiko and Mango, 2001) (see text). Scale bars: in A, 10 µm for A,C,E,G,I,K; in B, 10 µm for B,D,F,H,J,L.

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