Fig. 1. Wild-type and mutant gonad morphology. (A) Schematic diagrams of gonad morphology in the wild-type hermaphrodite (left) and the phases of DTC migration (right). Ventral and dorsal body wall muscles are shown in blue. Gonad arms (yellow) are surrounded by basement membranes (green). The uncolored part corresponds to the lateral hypodermis. Two DTCs (red) are generated at the anterior and posterior ends of the gonad primordium, located at the ventral mid-body, and migrate in a U-shaped pattern during gonad development. DTC migration comprises three phases: the initial migration on the ventral body wall muscle (phase 1), the ventral-to-dorsal migration along the lateral hypodermis (phase 2) and the migration along the dorsal body wall muscle (phase 3) (Hedgecock et al., 1987; Su et al., 2000). (B-G) Nomarski images of the posterior gonad arms of wild-type (B), mig-17(k174) (C), cogc-3(k181) (D,E) and cogc-1(k179) hermaphrodites (F,G). The gonads exhibit a meandering morphology in cogc-3(k181) and cogc-1(k179) mutants. The migration paths of DTCs are depicted by orange lines and arrowheads. Anterior is leftwards. Dorsal is towards the top. A, anterior; P, posterior; D, dorsal; V, ventral. Scale bar: 25 µm. (H) Percentages of anterior (left) and posterior (right) gonad arms that underwent normal or defective DTC migration. The migration defects were scored as the earliest phase during which a defect was evident. n=120 for each experiment. (I) Genetic interactions of mig-17 with cogc-3 or cogc-1. Percentages of anterior and posterior gonad arms having phase 2 migration defects. n=120 for each experiment. The error bars represent the mean±s.d. The values were calculated from the data collected from the first and second half of the animals examined.