The frog palate for studying mucus transport velocity and mucociliary frequency

The palate of the frog possess a pseudostratified epithelium with mucus secreting cells and numerous ciliated cells covered with a continuous mucus blanket of 4 to 8 micron thickness. This palate can be used as a simple model for studying mucus transport and giving rapid information on the transportability of pathological bronchial secretion by the ciliary mechanism. The analysis of the relationship between the rheological properties of sputum an their transport rates on the frog palate showed that the highest transport rates were obtained with sputum samples characterized by a high spinability (Sp greater than 70 mm) and an intermediate range of viscosity (25-180 P) and elasticity (SR = 4-12 units). The mucociliary frequency (Fm) of the frog palate was measured by a photoelectric method and analyzed as a distribution function of the ciliary frequencies by the Fast Fourier Transform method. Fm decreased significantly after mucus depletion and was restored when adding a drop of frog mucus collected on a freshly excised frog palate. On the other hand, it remained about 20% lower than the original predepleted value, when adding purulent sputum collected in patients with chronic bronchitis and cystic fibrosis. The frog palate appears as a valuable model for analyzing the mucociliary transport rate and also for studying the effect of pathological secretions on the ciliary beating frequency.