Intraspinal cyst formed of tissue proper to the tracheobronchial tract has been referred to as bronchogenic cyst. Six cell types of the cyst epithelium have been identified, i.e., ciliated cells, non-ciliated cells, goblet cells, basal cells, Kulchitsky's cells and undifferentiated cells. This report described the detailed morphological alterations of cilia of the lining epithelium of three cases of intraspinal bronchogenic cyst and compared the findings with the ciliary abnormalities of the tracheobronchial epithelium.

Ultrastructural abnormalities of cilia of the intraspinal bronchogenic cyst could be classified into five categories:

1. (A) Cilia showing addition, deletion or disorganization of axonemal minotubules.

2. (B) Swollen cilia containing a single axoneme in an excess amount of matrix: (a) normal 9 + 2 axoneme,(b) stretched axoneme bending toward one side, (c) abnormal axonemal pattern.

3. (C) Compound cilia with multiple axonemal microtubules ensheathed by a common ciliary membrane: (a) two or more normal 9 + 2 axonemes, (b) two or more normal 9 + 2 axonemes sharing doublets, (c) giant compound cilia with numerous normal and abnormal axoneme in random orientation, (d) compound cilia containing cytoplasmic organelles, (e) compound cilia with excessive matrix.