Some Observations on the Fine Structure of the Goblet Cells in the Nasal Respiratory Epithelium of the Rat, with Special Reference to the Well-Developed Agranular Endoplasmic Reticulum

Abstract

The fine structure of the goblet cells in the nasal respiratory epithelium of the rat was examined, in comparison with that of the intestinal goblet cells, by electron microscopy. The nasal goblet cells are characterized by the remarkable development of agranular endoplasmic reticulum in the apical cytoplasm; on the other hand, the intestinal goblet cells are completely devoid of this type of endoplasmic reticulum. In the nasal goblet cells mucus secretory granules are embedded in the networks of agranular endoplasmic reticulum, when accumulating in the apical cytoplasm. The basal half of the cells is abundantly provided with parallel arrayed cisterns of granular endoplasmic reticulum. The distribution pattern of endoplasmic reticulum as mentioned above is quite similar to that in the non-ciliated cells (Clara cells) of the terminal bronchiole. The study suggests that the nasal goblet cells of the rat are not only involved in the mucus secretion, but also play at least in part the same functional role as do the Clara cells. However, the functional implication of the agranular endoplasmic reticulum in the nasal goblet cells is in reality not known at present.