(A) An adult worm with body-wall muscle quadrants visible (orange). (B) A body-wall cross-section with cuticle, hypodermis, and basal lamina peeled away to reveal the basal membrane of two body-wall muscle cells. (C) A longitudinal section through a body-wall muscle cell. Dense bodies and M-lines attach actin thin filaments and myosin thick filaments, respectively, to the basal sarcolemma. (D) Locations of several different muscle attachment proteins. Loss-of-function for proteins shown in red causes the Pat developmental arrest phenotype. (E–J). PAT-4/ILK and PAT-3 integrin colocalize at muscle attachments in embryos and adults. (E) A wild-type, 420 min. embryo. PAT-4::GFP localizes to body-wall muscle attachments (arrow). The scale bar represents 2 μm. (F) The same embryo as that shown in (E) double stained with monoclonal antibodies MH25, recognizing PAT-3 integrin, and MH27, recognizing hypodermal-hypodermal cell junctions (included for developmental staging and orientation purposes). (G) An overlay of (E) and (F). Areas of PAT-4::GFP and integrin colocalization appear yellow. (H-J) Detail of body-wall muscle from a rescued pat-4(st551) adult hermaphrodite coexpressing (H) pat-4::yfp and (E) pat-3::cfp. Dense bodies (arrows), M-lines (arrowheads), and muscle-muscle adhesion plaques (brackets in H) are indicated. (J) An overlay of panels (H) and (I). Regions in which PAT-3::CFP and PAT-4::YFP colocalize appear white. The scale bar in (H) represents 5 μm. Right-click or control-click for larger image.