Fig. 9. Laminin A-deficient animals. (A) The pharynx (p) of predicted lam-3 null mutants do not properly form; cell bodies (arrowheads) are mispositioned into the surrounding tissues. In this animal the pharyngeal muscle cells (p) were visualized by expression of a myo-2::gfp transgene. (B) Electron micrograph of a lam-3 mutant reveals that the pharynx, which is normally cylindrical, is distorted because of the displacement of pharyngeal muscle (pm) and marginal (pmc) cells. The pharyngeal basement membrane is discontinuous and pharyngeal cells directly adhere to the body wall muscle (m) and epidermis (e) cells of the surrounding tissues (arrowheads). Asterisk indicates the lumen. (C,D) In the pharyngeal cells of lam-3 mutants, the apical membrane domain appears to develop normally as judged by the adherens junctions (C, arrowheads) that form by the lumen (asterisk). In addition, ectopic adherens junctions (D, arrow) also form at what should be the basolateral side of cells. Myofilaments in muscles and intermediate filaments in marginal cells may not assume their normal radial orientation (C, double-headed arrows). (E) In some cases, the lateral cell membrane appears greatly reduced in lam-3 mutants. Increased space between cells with what appears to be excess basement membrane forms between adjacent pharyngeal cells (arrowheads). Scale bars: 2 µm in B-E.