On the mechanics of mucociliary flows. III. Flow-velocity profiles in frog palate mucus.

Flow-velocity profiles over excised frog ciliated epithelium were obtained for the region within about 600 micron of the mucosa. Fluorescent particles were used as flow tracers. Both a control and an autologous mucus suspension were observed. The control culture medium was bounded by the walls of the observation chamber, and mucus was deposited on the epithelium as a blob after mixing it with tracers. In spite of the difference in boundary conditions the two profiles, normalized to maximum particle velocity and solution depth, were indistinguishable at heights over 60 micron from the mucosa. The near-mucosa profiles in contrast were unalike with mucus exhibiting a greater shear gradient than the control culture medium. It was concluded that ciliary contact is not necessary for generation of mucus flow provided the ciliary shear is not negated by the mucus "flake" or "slab" being in simultaneous contact with significant ciliostatic patches which would act as anchors.