The ultrastructural features (presence of microvilli and secretory granules) further confirm the glandular differentiation and its resemblance to the "superficial
indifferent cells" of the pseudostratified columnar epithelium or to the intermediate "transitional" epithelial cells lining the nasopharynx.[20] In addition, a few cells had intermediate features between adenocardnoma and undifferentiated carcinoma.