Function and morphology of respiratory cilia in situs inversus

The activity and ultrastructure of respiratory cilia were studied in 13 individuals with situs inversus but without serious respiratory complaints, in 8 patients with Kartagener's syndrome and in 50 healthy controls without situs inversus. In 3 individuals with situs inversus abnormal ciliary activity was found, comparable in every aspect to the ciliary activity in patients with Kartagener's syndrome. In 4 individuals with situs inversus a dynein arm deficiency was present in the cilia, with abnormal ciliary activity in 3 of them. The number of outer dynein arms per cilium differed significantly between the 3 groups (P less than 0.02). Apparently, situs inversus without serious respiratory complaints can be associated with primary ciliary dyskinesia. Based on the findings in this study, the incidence of primary ciliary dyskinesia in the Caucasian population appears to be 1:12,500.