Figure 4.—

vha-5 and rdy-2 mutants have enlarged excretory canals and cuticle secretion defects. TEM images of wild-type (WT), vha-5(mc38), and rdy-2(mc39) L1 larvae. (A) Cross section through the excretory canal; its outline is marked by a dashed line. Note the enlarged section of the canal in rdy mutants and its dark appearance in the rdy-1/vha-5 larva. The average canal section was 0.22 ± 0.05 μm² in wild-type L1 larvae, 0.69 ± 0.31 μm² in vha-5(mc38) larvae (P < 0.0005), and 0.44 ± 0.11 μm² in rdy-2(mc39) larvae (P < 0.0001). (B) Cross section through the epidermis. In vha-5(mc38) larvae, stacked sheets of membrane (arrowhead) originating from the apical plasma membrane are irregular, and the cuticle is irregular (arrow) and has partially detached from the epidermis (solid arrowhead). (C) The alae of the vha-5(mc38) larva are absent, and those of the rdy-2(mc39) larva have a flat structure, compared to control alae. Bars, 0.5 μm.