42 TOOTH-GERMS. 



and is composed of a small mass of mucous connec- 

 tive tissue, covered by a layer of cylindrical cells, and 

 joined to the buccal epithelium by the gubernaculum 

 deutis.^ According to Monsieur Magitot, the cement- 

 organ manifestly exists in the foal. The base of the 

 deu tine-germ has been found, but it disappears rapidly 

 after having performed its function. 



'^Development of the Dental Follicle. — On the free 

 borders of the maxillae, the epithelium of the buccal 

 mucous membrane forms an elongated eminence — the 

 dental ridge. Below this ridge the epithelium consti- 

 tutes a bud, which develops in size, and is sunk in the 

 mucous membrane. This is the enamel-germ. It has 

 a layer of cylindrical cells on its deep surface, and in 

 its center are round cells. After a certain time it is 

 only joined to the epithelium, as already said, by a very 

 thin line of cells, the guheryiaculum dent is. While this 

 enamel-germ grows downward, it covers, by its base, a 

 connective bud which rises from the mucous derma. 

 The two buds are reciprocally adapted to each other, 



* Concerning the gubernaculum dentis Prof. C. S. Tomes says 

 (" Dental Anatomy," p. 135): " Another structure, once thouglit 

 to be important, but now known to be a mere bundle of dense 

 fibrous tissue, is the ' gubernaculum.' The permanent tooth 

 sacs, durinor their growth, have become invested by a bony shell, 

 whicli is complete, save at a point near their apices, where there 

 is a fora'men. Through this foramen passes a thin fibrous cord, 

 very conspicuous when the surrounding bone is broken away, 

 which is called the gubernaculum, from the notion entertained 

 by the older anatomists that it was concerned in directing- or 

 effecting the eruption of the tooth. The guberuacula of the 

 front permanent tooth sacs perforate the alveolus and blend with 

 the gum behind the necks of the corresponding milk teeth, 

 those of the bicuspids uniting with the periosteum of the alveoli 

 of their deciduous predecessors." 



