Figure 9.—

Possible overgrowth of tissue at the anterior end of a mec-8; sym-3 double mutant. (A) The normal junction of the pharynx with the outer body as seen in the sym-3 single mutant of Figure 3D. The anterior and posterior extremes of the buccal cavity are indicated. (B) A schematic indicating the normal locations of the apical parts of the epithelia (Wright and Thomson 1981; Sulston et al. 1983) at the junction of the pharynx and the anterior tip of the body. The cuticle of the body, of the buccal cavity, and of the pharynx is indicated by a thick black line. The basement membrane of the pharynx is shaded. (C) The mec-8; sym-3 double mutant shown in Figure 3B. The arrows indicate a line of refractivity that tapers in the anterior direction beneath what appears to be an overgrowth of hypodermal material at the anterior end. (D) A schematic of the bulbous nose in C, with a thin black line indicating the tapered refractivity. Reminiscent of a normal anterior end, the thin line appears to be associated with the buccal cavity.