Microtubule-membrane interactions in ctenophore swimming plate cilia

The cilia in ctenophore swimming plates are organized into long rows and the cilia within each of the rows are connected to one another by interciliary bridges. The interciliary bridges form a type of intracellular junction and are periodically spaced at 15 nm intervals along the long axis of a cilium. The bridges bind adjacent cilia together even after dissolution of the ciliary membrane by non-ionic detergent. Interciliary bridges are attached to the compartmenting lamellae, which are paracrystalline structures composed of spherical particles which are periodically attached to the outer doublet microtubules at the sites to which the microtubule-membrane bridges are bound. It is proposed that the compartmenting lamellae are modifications of the ciliary microtubule-membrane bridge found in other eukaryotic cilia and that it is associated with a junctional complex that binds adjacent cilia together in swimming plates.