Recently improved methods for visualization of thin tissue sections by electron microscopy have been applied to the study of early changes in the bronchial epithelium of mice infected by inhalation of aerosols of influenza virus.
In confirmation of previous findings by the authors, inclusion bodies have been demonstrated in ciliated and non-ciliated cells of infected bronchial epithelium. In addition to 3 strains of mouse-adapted Type A virus, 2 unadapted strains gave qualitatively the same results. The inclusion bodies were found to be composed largely of particles of a size estimated to correspond to the known size of influenza virus. The viral lesion of the cytoplasm was also associated with linear formations which were thought to be abnormal forms of endoplasmic reticulum. Well developed microvilli were found on the ciliated borders of ciliated cells, but no evidence was found of viral growth in this region.