Expression of gfp::
sem-2 was first detectable in a subset of cells of the E and MS lineages in early gastrulating-stage embryos. The gfp::
sem-2 expression persisted through embryonic and larval development in many cell types, including vulval, hypodermal and intestinal cells. gfp::
sem-2 expression in the M lineage was first detectable at the 16-M stage in the SM mother cells, M.v(l/r)pa, and remained in both of their daughter cells, M.v(l/r)paa and M.v(l/r)pap. The presence of GFP::SEM-2 in M.v(l/r)pap was transient: GFP::SEM-2 was not detectable after M.v(l/r)pap differentiated into BWMs. However, GFP::SEM-2 persisted in the nuclei of the SM cells and all their descendants until the 8-SM stage, and became undetectable at the 16-SM stage.