Fig. 2. SDN-1 is required for the migration of neurons and coelomocytes. (A) Schematic depicting the migration of HSN neurons during embryogenesis. (B) In wild-type animals both HSN cell bodies (arrowheads) locate close to the vulva. (C,D) In sdn-1 mutants, HSN neurons fail to migrate to the vulva from their original position in the tail (C) or stall prematurely anterior to the vulva (D). Axons of mispositioned HSN bodies (arrowheads) that initially grow out incorrectly in a posterior direction eventually turn (arrows) and reach the nerve ring in the head. (E) HSN migration (adult stages) demonstrated by the genetic interaction of sdn-1 nulls with HS-modifying enzyme mutants. `% animal defective' represents the fraction of animals with at least one defective HSN neuron. Numbers are shown with the standard error of proportion. (F) Schematic of the six coelomocytes in wild-type and sdn-1(zh20) hermaphrodites. (G) In the wild type, coelomocytes born in the head migrate caudally during embryonic development, past the intestinal valve that separates the pharynx from the intestine (arrowhead). (H) In sdn-1 null mutants, coelomocytes are found in the head region, anterior and posterior of the intestinal valve (arrowhead). In order to define anatomical locations, some pictures were taken with DIC optics in the fluorescent channel (C,G,H). N, number of animals scored. Scale bars: 10 µm.