Changes in the ultrastructure of human respiratory cilia caused by the common cold were studied in 12 patients. The nasal mucosa was studied three times: on the first or second day after the beginning of symptoms, and 1 week and 3 weeks after the first biopsy. The damage was most severe at 1 week. The most remarkable finding was the loss of cilia and ciliated cells. However, the ultrastructure was usually normal, without any increase in tubular anomalies, as compared with the normal material of the previous reports. Three weeks after the beginning of the disease the number of cilia and ciliated cells had increased to nearly normal. However, as a sign of regeneration, immature short cilia (0.7 to 2.5 μm in length) were often seen. The ciliary orientation was uniform, dynein arms were normal, and there was no increase in the number of tubular anomalies. The results suggest that the impaired mucociliary function during viral infections is due to the loss of cilia and ciliated cells, rather than to ultrastructural anomalies in the cilia. The development of tubular anomalies and random ciliary orientation may require more extensive exposure to factors affecting ciliary function.
We have created a method for measuring the orientation of cilia in the respiratory epithelium. Ciliary orientation is the direction perpendicular to the plane defined by the central tubules of the cilia and is an estimate of ciliary beat direction. Ciliary orientation can be estimated by measuring the angle between the plane defined by the central tubules and a reference line. The standard deviation of these measurements describes the variation present in the beat directions of the cilia. The reference line must be so chosen that the majority of measurements falls at about the middle of the 0 degree-180 degrees range. We tested measurements by using both a glass angle measure and a semiautomatic image analyzer (IBAS I). The latter approach was faster and more reproducible. We made our measurements of normal tissues on samples obtained from two healthy adult non-smokers. Measurements were made in four areas of each sample, with 59-110 cilia in each. The differences between the maximum and minimum angles of the ciliary orientation in the same area varied from 167.9 degrees to 85.4 degrees from the reference line. The standard deviation varied from 18.0 degrees to 35.4 degrees and we consider this to be a normal variation in ciliary orientation. Of the cilia, 57% were within a standard deviation of 20 degrees.
Ciliary orientation was studied in 43 patients with the "immotile cilia" syndrome. Twenty-four of these patients had total situs inversus. One mucosal specimen was taken from uterine cervical epithelium, 2 were from bronchial mucosa and 40 from nasal mucosa. The orientation of the cilia was measured from micrographs using a semiautomatic image analyzer (IBAS I). The results from patients were compared with those of 10 control subjects. The mean standard deviation and its standard deviation of the angles of ciliary orientation was 39.7 degrees +/- 9.2 degrees in 43 patients and 27.4 degrees +/- 4.3 degrees in the control group. The difference between the groups is highly significant statistically (P less than or equal to 0.001). However, there were no statistically significant differences in the standard deviations of ciliary orientation between the fields sectioned near the cell membrane or near the ciliary tip. We were also unable to find any significant differences in the standard deviations of the ciliary angles in the specimens taken from brush biopsies and excisional biopsies. There were also no statistically significant differences between the standard deviations of the ciliary angles for the groups with or without situs inversus. If 35 degrees is considered to be the limit value for the mean standard deviation between normal and pathological specimens in our total material, this would give a specificity of 0.90 and a sensitivity of 0.72.
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