Consistent with the ubiquitous expression of
sqt-3 throughout the life cycle, the R584 antiserum intensely stains the hypodermal cells and cuticles of all stages. Reactive antigens are first detected in wild-type comma-stage embryos within the hypodermal cells. The signal localizes perinuclearly, presumably in association with the secretory pathway. At the threefold stage, coincident with cuticle secretion, the signal becomes progressively extracellular: by the late pretzel stage, all antigen is detected in alignment with the annular ridges of the embryonic cuticle.