326 MICROSCOPIC ANATOMY OP THE TEETH 



continuous band, often arranged as a distinct network, so 

 that the tooth at this stage is enclosed in an epithelial net 

 with open meshes. The sheath is continued to the forming 

 root tip, and as it nears this point it approaches more closely 

 to the dentine ; the network arrangement is not seen, but 

 two distinct layers of epithelial cells in close contact, which 

 at the tip of the root lie upon the dentine and turn round 

 it to extend into the connective tissue of the forming pulp 

 in a long curling band, the termination of this band bc-ing 



FIG. 214. Hertwig's sheath surrounding forming root. Eoot about half 

 formed. The sheath is seen to be in contact with the dentine at the 

 lower end (h 2 ) ; the osteoblasts and depositing cement are seen to the inner 

 side of h l ; h 3 . the curling band of Hertwig's sheath separating the pulp (p) 

 from the connective tissue of the follicle. ( x 150.) 



formed by the reflection of the two layers of cells, which form 

 a close loop. A similar loop is continued from the opposite 

 side of the root tip, but these two loops do not meet, but 

 leave a space between them occupied by the developing pulp 

 with its entering nerves and blood-vessels. It can be seen in 

 figs. 214, 215, and 216 that the odontoblasts and the form- 

 ing dentine are completely cut off from the surrounding 

 connective tissue of the follicle by this epithelial band. An 

 examination of the forming root at different stages of growth 

 shows that this epithelial inflection in man gradually shortens 



