CILIARY MOTILITY AND SURFACE-MORPHOLOGY OF CULTURED HUMAN RESPIRATORYEPITHELIAL-CELLS DURING CILIOGENESIS

We used human respiratory epithelial cells in floating culture to stud y the motility and surface morphology of the cilia during ciliogenesis . Ciliary motility and surface morphology was examined by a high-speed video system and electron microscopy, respectively. On day 8 of float ing culture, but rarely before, cells with numerous moving short cilia with mean ciliary beat frequency (CBF) of 17.8 +/- 2.5 Hz (mean +/- S D) were seen. The mean CBF was highest on day 10 (19.6 +/- 3.9 Hz) and reached 17.4 +/- 2.5 Hz on day 14. The ciliary beat amplitude (CBA) w as recognized on day 8, abruptly increased on day 9, then continued wi th aging of the culture. The intracellular coordination of ciliary bea ts was poor on day 8 with random beat direction but improved up to day 12 when the intracellular uniform beat direction was established. How ever, intercellular coordination remained absent even on day 14. Resul ts suggest that immature short cilia have a rigid beat pattern. With t he elongation of the cilia and the resulting whip-like movement, the c iliary beat was gradually synchronized. Although a ciliary elongation seems to be required for making intracellular coordination, other fact ors are involved in intercellular coordination. Also, a high CBF does not always indicate the activity of mature cilia.