The pronephic duct is a model for studies of epithelial polarity

The Na+/K+ ATPase is a membrane bound ion pump normally located basolaterally in kidney tubule and collecting system epithelia, consistent with its role in electrolyte and solute resorption from the glomerular filtrate.

Sections of wild type embryos (wt; left) show that Na+/K+ ATPase immunoreactivity (light brown HRP reaction product) is restricted to the basolateral surfaces of pronephric duct epithelial cells. In contrast, several of the pronephric mutants show altered localization of the Na+/K+ ATPase. In dbb, staining is primarily apical while basolateral cell surfaces show greatly reduced staining. flr also shows this reversed pattern of staining.