324 MICROSCOPIC ANATOMY OF THE TEETH 



We thus see that the sheath of Hertwig is not a downward 

 extension of the cells of the enamel organ, and we have to 

 look elsewhere for its origin. 



In figs. 212 and 213 the strand of cells composing the 

 sheath can be seen passing to the outside of the enamel at 

 the point of junction of the follicle with the tooth, and the 

 termination of the cell layers of the enamel organ is distinctly 



e.o 



FIG. 212. The junction of the follicle with the tooth at the neck. 

 e.o. Enamel oigan ; h. Her twig's sheath passing to the outer side of enamel 

 organ ; o. osteoblasts and thin layer of cement ; d. dentine. ( x 150.) 



visible. It is seen that the sheath of Hertwig has no connexion 

 whatever at this point with the enamel organ, but is com- 

 pletely shut off from it within the connective tissue of the 

 follicle. 



The strands of epithelial cells of which the sheath is com- 

 ' posed pass to the coronal part of the follicle, and appear 

 to be derived from the cell elements which are there present 

 in such abundance. 



While these cell extensions are plainly seen at the neck 

 of the tooth passing to the outer side of the terminal portion 

 of the enamel organ, they cannot be traced very far into the 



