Function and Properties of Epithelial Mucus

Abstract

In the case of ciliated epithelia over which transport of particulate matter takes place, mucus has been shown to fulfill the role of mechanical coupler (Sadé, et al., 1970). Whereas ciliary beat provides the source of motion, the fresh secretion of mucus is essential for converting this motion into the movement of particles over the epithelial surface. For example, on the palate of the frog, the mucociliary system provides the means of transporting food particles from the mouth to the gullet. When such a palate is excised it continues to transport particles, but repeated loading of the palate, say by little steel balls, gradually exhausts it of its mucus. Particle velocity drops and eventually reaches zero even though ciliary beat continues. The palate epithelium, locally has become depleted of its mucus which is found accumulated along the cut edge. When some of this mucus is returned to the epithelium, transport of the steel balls is resumed at the original velocity. Such a biological preparation can be used, therefore, to test whether other systems can be applied to the epithelium and substitute for mucus. It can also answer the question of what properties they must possess to provide this function.