STRUCTURE AND GROWTH OF INCISOR TEETH 87 
curs between the typical enamel-organ and the stratified squa- 
mous epithelium (fig. 27). As one follows the innermost layer 
of the enamel-organ forward, the cells become shorter, until 
they are cubical and finally flattened in shape. Here the other 
layers also lose their regular arrangement, and form, with the 
preceding, a thin layer of stratified cells. This layer can be 
followed directly into contact with the epithelium of the gingivus. 
Fig. 27 Longitudinal section of the apex of the tooth of a 5-month albino 
rat, showing at a the position of the outward prolongation of the remains of the 
enamel-organ, and at b the more granular osteodentine filling in the apex of the 
pulp chamber. X 10. 
The cells, however, do not lose their identity in the surface 
epithelium but remain separate as a thin layer lying against 
the enamel (fig. 27, a). This thin layer of epithelium, there- 
fore, represents the ultimate fate of the enamel-organ after it 
has completed its functional activity. It is being continually 
pushed out and its most anterior part must be continually being 
lost. 
