Fig. 4. Domains of expression of rnt-1. (A,B) rnt-1(e1241); him-5(e1490) embryos carrying a rescuing rnt-1::GFP reporter construct. (A) rnt-1 expression is first seen in seam cell nuclei in embryos around 260 minutes after fertilisation. Dorsal view. Seam cells are visible on one side of the embryo (the left side) in this focal plane. Seven out of the nine H and V seam cells, labelled H0-H2 and V1-V4 are visible; V5 and V6 are out of focus. The T seam cell is ventral at this stage of development (Sulston et al., 1983). (B) Seam cell expression of rnt-1::GFP at the 1.5-fold stage. Lateral view. H and V seam cell nuclei are labelled. Again, T is out of focus, as is V6. Anterior is towards the left in both panels. Scale bar: 20 µm. (C,D) Seam cell expression of rnt-1::GFP in L1 larvae. (C) Lateral view. Seam cell nuclei are labelled. V5 is dividing (asterisk). Expression in H0 is fainter than in the other seam cells. Scale bar: 20 µm. (D) Corresponding Nomarski image. The outline of the dividing cell is clearly visible (asterisk). Inset is a higher magnification image of V3 (arrowhead) showing the morphology of seam cells. Anterior is towards the left in both panels. (E) Expression of rnt-1::GFP in body wall muscle nuclei. This is the same animal as in C, slightly different focal plane. Body wall muscle cells are present as four longitudinal rows at this stage, one ventral row and one dorsal row on each side of the animal. Two out of the four rows (one dorsal and one ventral) are visible in this lateral view (arrows). (F) myo-3::GFP body wall muscle reporter for comparison. Again, two longitudinal rows of cells are visible in this lateral view (arrows). Anterior is towards the left. Scale bar: 20 µm. (G) Male tail expression of rnt-1::GFP in early L3 showing ray precursor cells R1-R9. R5/6 and R8/9 have yet to divide. The V5-derived cell labelled with an arrowhead forms part of the body seam. Posterior is towards the right. Scale bar: 20 µm.