Flask cells and flask-shaped glandular cells of amphibian skin specifically produce fucose-rich glycoproteins

A battery of horseradish peroxidase-conjugated lectins has been employed as a cytochemical tool for the labelling of specific cell types in amphibian epidermis. Among the lectins used, onlyUlex europaeus I (UEA I) showed specific reaction with the cytoplasm of flask cells. In addition, UEA I stained flask-shaped secretory cells in dermal glands and a reaction on glandular ductal cells was also observed. At the electron microscopic level, lect-in binding was found in granules distributed among mitochondria in the cytoplasm of flask cells and in larger mucous granules of flask-shaped glandular cells, which were released into the lumen. UEA I also stained the extracellular space above flask cells. The labelling was due mainlty to a glycoprotein of mol. wt. approx. 27 kDa. Structural and cytochemical similarities between flask cells and flask-shaped cells of dermal glands could be a consequence of a common secretory role of both cell types.