146 



NORMAL HISTOLOGY. 



The tooth comprises the dentine, the enamel, and the cemen- 

 tum. 



The dentine, or ivory, principally contributes the bulk and the 

 characteristic form of the tooth, completely enclosing a central pulp- 

 cavity, except where the narrow nutrient canal, admitting the blood- 

 vessels and nerves to the pulp, pierces the apex of the fang. The 

 dentine is composed of a matrix or ground-substance, which, as 

 that of bone, must be regarded as modified connective tissue, 



formed of bundles of 



FlG - J 73- fibrous tissue intimately 



united and subsequently 

 impregnated with calca- 

 reous salts. 



Piercing the ground- 

 substance and appear- 

 ing under low amplifica- 



Section of dried human tooth 



f* showing portions of enamel and 



Longitudinal section of molar tooth of kitten : a, pulp-cavity, dentine : a, ground-substance of 

 continued by canals (_/") to apices of roots ; d, dentine ; e, en- dentine ; b, branching dentinal tu- 

 amel ; c, cementum ; /, alveolar periosteum ; n, neck of tooth ; bules ; c , terminal zone of tubules 

 b, osseous tissue of jaw. within the enamel (d). 



tion as a radial striation, the dentinal tubules extend the entire 

 thickness of the dentine as minute channels ; they are seen espe- 

 cially well in sections of the dried tooth in which the canals are 

 filled with air. Starting from the pulp-surface with a diameter of 

 20-26 /*, the dentinal tubules pass in a slightly wavy and spiral 

 course through the dentine, to terminate in irregular clefts, the 

 interglobular spaces, situated at the juncture of the dentine with 

 the enamel or the cementum. 



