Ultrastructure of the respiratory mucous epithelium of the canine nasal cavity

Abstract

The fine structure of the mucous epithelium of the respiratory region of the canine nasal cavity was characterized through the use of the electron microscope. The surface epithelium can be classified as pseudostratified ciliated columnar type composed of ciliated cells, goblet cells, brush cells, basal cells and basement membrane.The ciliated cell possessed cilia which were approximately 5.5μ long and 0.2μ wide, and intercilialy microvilli which measured 1.5μ in length and 80mμ in width on its free border, and the microvilli were bifurcated sometimes. The cilia contained nine pairs of peripherally arranged longitudinal tubules and one central pair. At the tip of the cilia nine peripheral pairs transformed into nine singlets. At the base of the cilia there were a basal body, a basal foot and a rootlet fiber ended in a granular zone.The goblet cells were classified to three types according to the amount of mucous droplets. They were a stout goblet cell filled with numerous droplets, one that possesses several mucous droplets, and thin one without a mucous droplet at all. All of them were characterized by their electron opaque features and thick population of the endoplasmic reticulum and other cell organelles.The brush cell was characterized by its short, relatively uniform filiform projections from the free cell border. The filiform projections resemble the striated border of the intestine.The basal cells in contact with the basenment memcrane did not reach the free surface, they were asteroid with numerous protoplasmic projections. Also the cells of intermediate height had no free surface. Both the intermediate and low cells were electron opaque.The basement membrane was rather homogeneous, structureless, electron medium opaque membrane which possessed semidesmosomes.Acknowledgment. The authors wish to express their appreciation to Dr. A. F. WEBER, Director cf the Department of Veterinary Anatomy, College of Veterinary Medicine, University of Minnesota for the critical advice to investigate the nasal mucous membrane of the respiratory region from the view point of comparison with the olfactory region. Lt. Colonel J. F. METZGER and Major C. O. BURDICK, in the 406th Medical Laboratory, US Army Medical Command in Japan, made available excellent space and facilities for the electron microscopic work, and the generous technical assistance of Mr. MITSUHASHI and Mr. YAJIMA has greatly facilitated the study. Also the authors are grateful to Major R. J. WARNE and Miss NAKAMURA for their assistance in the preparation of this manuscript. Dean OMORI, Prof. KIMATA and Prof. KUWABARA of the College of Agriculture and Veterinary Medicine, Nihon University gave generous considerations for accomplishment of this study. These aids are gratefully acknowledged.