148 H. J. HoHLiNG, H. Themann, J. Vahl 



The interaction of ions which leads to the "binding" of phosphate with the side 

 groups of the collagen fibres as matrix presumably accounts for the fact that the 

 lattice of these nuclei is still in a less organized state. Moreover, we concluded that 

 by this reciprocal action collagen subfibers ("spiral lattices" according to Sasisekha- 

 RAN and Ramachandran, 1957) are "cemented", for the diameter of these dark 

 apatitic elements (60 — 80 A) is within the range of the diameter which might be 

 assumed for collagen subfibers from equatorial low angle diffraction spots got by 

 Ramachandran and Sasisekharan (1960). By this apatitic "cementation" of collagen 

 subfibers the macromolecular arrangement and thus the cross-striation of the collagen 

 fibers is lost. 



We concluded that the light-looking apatite crystallites (Fig. 1, arrow 1) are 

 generally formed from the thin, dark-looking apatitic formations when there is a 

 sufficient delivery of ions for apatite formation and sufficient micro-space for 

 expansion of the crystallites in width because in the areas of the dark-looking 

 apatitic formations the thicker, lighter-looking apatite formations mentioned above 

 gradually develop. The fact that these elements gradually become lighter may result 

 from an increasing organization of the atoms in the lattice. 



'^2 ^^ 







Ml 





Fig. 2. Ultrathin section of carious dentine. By the decomposition oi:' the thin, dark looking apatitic 

 "cemented" coUagen-subfibres were set free again and could combine to thicker collagen fibres with cross- 

 striation. (The arrows indicate light-looking apatite crystallites which lie at random in carious dentine.) 

 Magnification: 198 000:1 



It was observed that the distance from one row of the light-looking parallel 

 apatite crystallites to the next lies within the range of the collagen macro-period 

 (640 A-period) (Carlstrom and Glas, 1959; Glas, 1962; Quigley and Hjorting- 



