Ciliated tracheal epithelium is arranged in a polarized pattern orient
ed according to the inferior-superior axis of the trachea and is respo
nsible for the transport of mucus toward the larynx. In this study, ci
liary beat orientation and the influence of external factors on mucoci
liary clearance direction were studied in rabbit inverted cervical tra
cheas. The animals displayed normal respiration postoperatively. After
16 weeks, airway clearance was studied by observation of the movement
of silicone particles placed in the inverted segment and in normal pa
rts of the ciliated epithelium. Cilia exhibited unidirectional and coo
rdinated movement within inverted tracheal segments. As shown by the d
irection of effective flow produced by beating cilia and by scanning e
lectron microscopy, the cilia in the inverted segment beat in the oppo
site direction from the cilia in the remainder of the trachea. This st
udy demonstrated that ciliary orientation is irreversibly determined,
but the reversal of ciliary beating within the cervical trachea had no
adverse effects on the survival of the animals.