The ultrastructure of mouse lung; a note on the fine structure of mitochondria and endoplasmic reticulum of the bronchiolar epithelium.

Abstract

A few aspects of the fine structure of bronchiolar epithelium have already been presented (4). The two types of cells, ciliated and non-ciliated, differed in their cytoplasmic structure. The ciliated cells contained only a few mitochondria, and a few vesicles of the endoplasmic reticulum, whereas non-ciliated cells showed numerous large mitochondria and a very well developed endoplasmic reticulum. It was also shown (4) that the mitochondria of non-ciliated bronchiolar cells appeared either as long and filamentous or as spherical, even within one and the same cell, and that the endoplasmic reticulum could assume the form of paired double membranes as well as of vesicles or tubules. The difference in appearance of the endoplasmic reticulum in ciliated as compared with non-ciliated cells and the varying forms of the reticulum in the non-ciliated cells had been recognized earlier by other authors (1). The present brief report further illustrates the spherical mitochondria and the endoplasmic reticulum of non-ciliated bronchiolar epithelial cells. The methods of tissue processing and the technique used to select a small bronchiole for sectioning are the same as in earlier reports (2, 3, 4).