How are different ciliary beat patterns produced?
In this paper, the generation of different patterns of beat is discussed in terms of the internal mechanism of the cilia. A simple classification is proposed for the wide variety of patterns of planar beating. Ctenophore comb plates can show four types of movement: arrest, reverse beating, flagellar beating and forward beating. Other types of cilia show several or all of these beat patterns. Following stimulation of the organism these different beat patterns occur in a definite sequence which is the same in all cases. There is some evidence in each example that change in beating activity from the normal pattern towards the arrest or reversal response is associated with an increase in intraciliary Ca2+ concentration, and it is suggested that the sequence normal ciliary beat leads to symmetrical flagellar beat leads to reverse ciliary beat leads to active arrest represents the response of the axoneme mechanism to progressively increasing levels of intraciliary Ca2+ concentration, different patterns of beat resulting from different patterns of activation of the dynein arms within the axoneme.