In this method, the intestinal lumen of Caenorhabditis elegans (C. elegans) is labeled with a fluorescent fluid-phase marker, Texas Red-dextran. Since dextran conjugates are membrane impermeable, animals fed with it show a red fluorescent signal in the lumen of the intestine. Texas Red-dextran in the lumen is not efficiently endocytosed by intestinal cells and is not effectively transported to the body cavity paracellularly. It is useful to determine whether round-shaped membrane structures are invaginations from the apical membrane or cytoplasmic vesicles. If the barrier function of the intestinal epithelium is impaired, Texas Red-dextran can leak from the intestinal lumen to the body cavity. Therefore, this method can be used to visualize apical membrane morphology in intestinal cells and to investigate the barrier properties of the intestinal epithelium.

C. elegans (线虫)

Intestine (肠)

Apical membrane (顶膜)