SOME PROBLEMS OF CILIARY STRUCTURE AND CILIARY FUNCTION 567 



Discussion 



GoLDACRE : Is there any direct evidence that these (9 + 2) filaments are the 

 motile element ? Have they ever been fixed and viewed in the contracted state ? 



Afzelius: Xo. It is obviously important to investigate a ciliated epithelium in 

 which the metachronal waves of the cilia have been preserved. The diflFerences 

 that would be found with regard to the dimensions or the mutual positions of the 

 filament would probably tell us much of the mechanism of the cilia. This project 

 is, however, not as simple as one would expect. I have not been able to fix the 

 metachronal waves. At present it is not known what is the contracted state of a 

 cilium, or even whether the ternis contraction and relaxation can be applied to 

 certain phases in ciliary and flagellar movements. 



Sheldon: In the light of recent experiments from Portugal and looking at your 

 picture do you think the cilia are oval or round ? 



Afzelius : You are talking about the paper by Serra in the last issue of Exper- 

 mental Cell Researcli [20, 395 (i960)]. I think the ciliary cross-section is round. 

 The author might however be correct when he emphasizes that there are other 

 factors than the mechanical work of the cilia that determine the morphology of 

 the cilium. 



RuxNSTROM : What other factors will there be ? 



Afzelius: According to Serra the mode of duplication of the basal body 

 determines some features of the ciliarv structure. 



