Ultrastructure and movement of the ependymal and tracheal cilia in congenitally hydrocephalic WIC-Hyd rats.

The aim of the present investigation is to determine whether or not hydrocephalus occurring in hydrocephalic Wistar-Imamichi strain rats (WIC-Hyd) is caused by functional and structural disorders of ependymal cilia. Ultrastructures and movement of cilia in the ependyma of the lateral, III and IV ventricles and aqueduct of Sylvius and in the trachea walls of the animals were examined by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and light microscopy using a phase-contrast microscope equipped with a high-speed video recording system. SEM revealed that a marked decrease in the length and number of cilia in the ependymal and tracheal walls occurred in affected male WIC-Hyd. This finding was noted even before the development of ventricular dilatation and was not related to the degree of ventricular enlargement after development of hydrocephalus. A moderate decrease in length and number of cilia was also seen among the normal ciliary tufts in affected female rats which developed a mild degree of hydrocephalus. TEM cilia findings included abnormal axonemal structures such as a lack of dynein arms and displacement of microtubules. The incidence of these ultrastructural abnormalities was found to be greater in affected male rats than in affected female rats. All cilia in affected male rats before and after development of hydrocephalus were immotile. A variety of movement disorders such as immobile, rotatory, and vibratory cilia were observed beside normally beating cilia (motile cilia) in affected female rats which never developed hydrocephalus as severe as that seen in affected male rats.(ABSTRACT TRUNCATED AT 250 WORDS)