118 



F. G. E. Pautard 



other hand, in a detailed study of amelogenesis, makes it clear that the pattern of the 

 organic stroma before mineralization so closely resembles the crystal arrangement 

 that detailed analysis is essential to distinguish the one from the other. 



Fig. 3. 

 opteru: 

 Fixed 



Electron micrographs of analogous mineralized tissues, a. T.S. Fringe hbre 

 ; borealis. Unfixed -130,000. b. Edge of mineralizing zone in the epiphysi: 

 glutaraldehvde'cadmium chloride • 130,000. Areas of electron-dense perlphei 



Our own studies of amelogenesis in the rat agree closely with those of Ronnholm 

 (1963) except that improved fixation techniques suggest that the edge of the amelo- 

 blast might be continued into fine ribbon-like processes which are first loaded with 



