At the beginning of embryonic morphogenesis, all ten pairs of lateral epidermal cells, the seam cells, express
cdh-3::lacZ.
cdh-3::GFP expression in these cells is observed at hatching and throughout subsequent postembryonic development. During the last larval stage (L4) the 15 pairs of seam cells generated during larval development fuse to form two continuous lateral syncytia, surrounded by
hyp7.
cdh-3::GFP expression correlates with seam cell identity during these postembryonic divisions; it is not observed in daughters that fuse with
hyp7 or adopt other fates. In embryos undergoing morphogenesis, lacZ is expressed in a single large nucleus, whose size and position is consistent with that of the excretory cell. This identification is reinforced by the observation that in many newly hatched L1 larvae, low levels of GFP expression are visible in the excretory cell. This expression of
cdh-3-reporter genes was observed only during late embryogenesis and in some newly hatched L1s (the latter may be due to perdurance of the GFP fusion protein), but not at later stages. Several other cells expressed the
cdh-3 reporter constructs during embryonic morphogenesis; as in the seam cells this expression continued upon hatching. In the tail two cells,
hyp10 and
hyp11, show strong GFP expression that persists only during the first larval stage. Strong expression was observed in cells that form interfacial epithelia between the intestinal epithelium and the epidermis. Two cells that form part of the rectal epithelium, designated F and U, express
cdh-3::GFP during embryonic morphogenesis and throughout larval development. In the anterior of embryos undergoing morphogenesis there were several cells expressing
cdh-3::lacZ, and in larvae and adults, GFP expression is seen in nine cell bodies located just anterior to the first bulb of the pharynx. Processes extend anteriorly from these cell bodies and terminate at the level of the buccal capsule. Based upon the location of the cell bodies and the morphology of the processes, these cells were identified as the anterior and posterior arcade cells.