Abstract
The guinea pig middle ear mucosa, including that of the eustachian tube, was embedded in Epon or Lowicryl K4M. Thin sections of the mucosa were stained with wheat germ agglutinin (WGA) -gold complex, and examined under electron microscope. WGA-reactive glycoconjugates were primarily localized over the glycocalyx made of fine filaments surrounding microvilli and over mucous blanket overlying cell surfaces. In addition to this apical surface labeling, several intracellular structures such as Golgi apparatus and all three types (electron-lucent (EL), intermediately electron-dense (ID), or electron-dense (ED) type) of secretory granules were heavily labeled. Among the granules EL granules showed stronger labeling than the others. The results presented here indicate that WGA-binding sites are closely associated with the secretory granules and with the luminal surface structures of the middle ear epithelium, suggesting the distribution of glycoconjugates in both secretory products and membrane consituents.
