268 



R. M. Frank 



The last ultrastructural problem to be discussed is the innervation of predentine 

 and dentine. It is impossible to review all the very extensive literature on the light 

 microscopical investigations dealing with the presence or absence of nerves in this 

 tissue. It can be mentioned, however, that Baud and Held (1953), Fearnhead (1957, 



Fig. 10 



Fig. 11 



Fig. 10. Electron diffraction pattern of the intertubular substance 



Fig. 11. Selective area electron diffraction pattern of peritubular dentine with line arcing indicative of pr 



ferential orientation of the apatite crystals 



