158 



MICROSCOPIC ANATOMY OF THE ORGANS, 



straight course and do not often branch to form canals of the 

 same calibre. In the neck they are slightly wavy. In the 

 root they are more uneven, and branch frequently to form 

 equal-sized canals (Szymonowicz). The peripheral ends of 

 the main canals are different according to their surroundings. 

 In the crown just under the enamel they break up into finger- 

 like branches (Plate IX.), some of which run past the 

 boundary line between the enamel and dentine for 10-40 ^ 



From a ground-section through the parts of the dentine, near the pulp, of a human 

 canine tooth which has been impregnated with pigment. The dental canaliculi are cut 

 across and are joined together by side branches. X 400. 



into the cement substance joining the enamel prisms (Fig. 117). 

 Dilatations are observed often at the ends of these branches. 

 Most of the main canals, however, end blindly at the border of 

 the enamel. 



In the lower part of the tooth the main canals do not leave 

 the dentine, but end blindly at the border of the cement i. e., 

 at Tomes' granular sheath. They often reach as far as the 

 spaces of the sheath, which are filled with uncalcified ground 

 substance (Fig. 116). Rarely they arch over and form with 

 neighboring canals a kind of loop. 



The part of the ground substance immediately surrounding 



