164 



THE DISSECTION OF PIG EMBRYOS FOR STUDY 



The enamel is laid down first as an uncalcified fibrillar layer which later becomes 

 calcified in the form of enamel prisms. From the ends of the cells project cutic- 



Dental lamina 



Epidermis 





3L **?** / 



lfe'. : . ye 



-Dental papilla. 



FIG. 156. Section through the upper first decidual incisor tooth from a 65 mm. human embryo. X 70. 



Tip of tongue 



Epidermis of lip 



e^ x tfj"~ "**_L Enamel organ of tooth 



Submaxillary duct ~ *- -^pft ?s2s- \.tM-.4 



Sublingual duct ^^ t 5^f - . ~4 Dental P a P illa 



, - .;<& . - - - ^^| 



Meckel's cartilage 

 Bone of mandible 



FIG. 157. Parasagittal section through the mandible and tongue of a 65 mm. human embryo showing 

 the position of the anlage of the first incisor tooth. X 14. 



ular fibers known as Tomes' processes (Fig. 158). The enamel is formed first 

 at the top of the crown of the tooth and extends toward the root over the crown. 



