A three-dimensional model for ciliary motion based on the internal 9 + 2 structure

Here we present, to our knowledge, the first modelling platform that enables simulations of threedimensional (3D) motion of multicilia arrays at a detailed level. It consists of three building blocks: (i) geometric equations for tracking the 3D motion of the cilia, (ii) a hydrodynamic description of the ciliary system, and (iii) model equations for the internal bend generating based on the 9 + 2 structure. The model generates seemingly realistic 3D beat patterns and demonstrates metachronal coordination that evolves autonomously as a result of the hydrodynamic coupling between the cilia. We study the effect of the twisting motion within the cilia and propose a conjecture on a possible role of the radial spokes system.