ANALYSIS OF 3-DIMENSIONAL CILIARY BEATING BY MEANS OF HIGH-SPEED STEREOMICROSCOPY

Results are presented on the analysis of three-dimensional motion of c ompound cilia or cirri in voltage-clamped specimens of the protozoan S tylonychia mytilus. Time series of three-dimensional data were obtaine d by using the anaxial illumination method for simultaneous recording of stereoscopic video images. Data processing involved the following s teps: determination of a reference coordinate system based solely on f eatures present in each stereo-pair; tracing of cirral axes in digitiz ed images, conversion to parameter curves by means of least-squares po lynomial approximation, conversion of pairs of two-dimensional data to a series of three-dimensional data; correction for distortion due to projective shortening and conversion to a series of polynomial triplet s, and analysis of the periodical components of the motion pattern in the frequency domain. Reconstructed beating cycles show typical differ ences between hyperpolarization-induced ciliary activity and depolariz ation-induced ciliary activity. Reconstructions of the motion of the b asal segment of a cirrus are in agreement with existing data. Analysis of the curvature and torsion of a cirral axis during beating does not reveal any simple pattern of propagated activity within the axoneme. The return stroke may be subdivided into two phases. First, a curvatur e peak develops proximally. Secondly, a region with increased torsion arises more distally and spreads out in proximal direction. Both curva ture and torsion return to minimal values by the beginning of the powe r stroke.