NHX-3 appeared to be associated with intracellular membranes. NHX-3::GFP expression was identical in both translational and transcriptional fusions and occurred primarily in the hypodermal cells of the main body syncytium; in addition, in adult animals the uterine cells in the region closest to the vulva were intensely labeled, as were the spermathecal junction cells. The uterine cells are likely
ut1, a toroidal cell proximal to the vulva. In addition, labeling was detected in socket cells and the excretory pore cell. The fluorescent expression pattern resembled dots distributed randomly throughout the cells. Under maximum resolution, these structures were seen to be elliptical, with circumferential labeling. In contrast to the usual suspects (Golgi, endoplasmic reticulum, endosomes, or mitochondria) these dots may represent storage granules, because hypodermal cells function as a major storage depot for granules and lipid droplets. Alternatively, the structures could be one of two other organelles that are unique to hypodermal cells, multivesicular bodies, or Ward bodies, which presumably play roles in the hypodermis-specific functions of secretion of cuticle components or the phagocytosis of apoptotic cells.