Comparison of Ciliary Activity under In Vitro and In Vivo Conditions.

Abstract

Normal ciliated epithelia removed from the animal body and kept under optimal conditions vibrate vigorously for long periods of time. Epithelium from the frog's pharynx is a classical example of the unceasing vibratility and indefatigability of cilia; it has been kept viable in tissue culture for as long as 56 days. It has therefore been generally assumed from results of methods available for study that cilia under in vivo conditions show a similar unceasing activity. McDonald, Leisure, and Lenneman, Seo, and Pohle in their experiments on frog's epithelium in vivo, regard the normal state of the cilia as active. The need of methods which will permit direct observation of ciliary activity has been emphasized, and the present report deals with the application of a method by which cilia arranged in a field, as they are in the pharynx of the frog and the nasal cavity and sinuses of higher animals, may be kept under direct observation, thus eliminating the indirect evaluation of movement of inert particles applied to the surface, which method is of value in a study of direction of ciliary movement but not in the determination of extent or continuity of movement. The use of such a direct method reveals that when no stimulating factors are present the cilia are not active. A strong concentrated beam of light passed through a water filter is thrown on the ciliated surface at as an acute angle as possible. The microscope is focused upon one of the many “high-lights ”reflected. A microscope tube fastened to a sliding rod with adjustable joints permits focusing the microscope at any angle and thus quickly and easily aligning the optical axis with the reflected beam from the “high-light”.