Required for epithelial tube development and shaping (PubMed:27482894, PubMed:33141826). Involved in the morphogenesis and function of the three unicellular tubes of the excretory system, the canal cell, the duct cell and the pore cell (PubMed:7476875, PubMed:27482894, PubMed:33141826). Also plays a role in cuticle development, alae formation and shaping of the vulval lumen (PubMed:27482894). Required for larval development (PubMed:7476875, PubMed:27482894, PubMed:33141826). Localizes to fibrils in the vulval luminal space. Expressed in external cuticle-producing epithelial cells including the epidermis, vulva, rectum, excretory duct and excretory pore. Secreted in the region between the embryo and inner layer of the eggshell. Expressed in excretory canal cells of embryos and at the 1.5-fold stage of embryonic development accumulates in the lumen of the excretory duct and pore. Expression ceases in the lumen of the excretory duct and pore prior to cuticle secretion. Thereafter expressed transiently in the lumen of the excretory duct and pore in the latter phase of each subsequent larval developmental stage. During the molt phase of larval development, accumulates in the space in between the new and old cuticles. During the L4 stage of larval development, accumulates in the vulval lumen. The ZP domain is required for localization at the apical cell membrane, secretion and excretory tube and vulval lumen expansion. Cleaved at the C-terminal domain. Lethal at the larval stage of development. Defects in the development of the excretory system during embryogenesis and the early stages of larval development. Dilated lumens of both the excretory canal cell and excretory duct which become apparent between the early and mid 3-fold stages of embryogenesis and increases in severity as development progresses. Lumen dialation may be as a result of fluid accumulation due to blockage of the lumen. At around the time of hatching, the autocellular junction, which usually seals the excretory pore tube, is absent. Detached excretory duct and pore cells, which usually connects the excretory canal cell to the outside environment for excretion. Irregular morphology of the epidermis and vulva in larvae at the L1 stage of larval development.