THE TEETH. 



65 



Fig. 197. 



in breadth, with very beautiful, vesicular nuclei, and distinct, 

 single or multiple nucleoli; they are arranged close together 

 over the whole surface of the pulp (fig. 197), like an epithe- 

 lium, though not so sharply 

 defined internally as it would 

 be, but gradually passing, at 

 least apparently, by smaller 

 cells, into the parenchyma. 

 In vascular pulps (fig. 197), an 

 additional boundary line may 

 be traced, inasmuch as the 

 capillary loops in which the 

 vessels terminate, do not pene- 

 trate between the cylindrical 

 cells, but end close to one 

 another upon their inner sur- 

 face; so that, considering that 

 the dentine is produced by 



the cells in question, we might be justified in terming them 

 the dentinal membrane, or membrana eboris. The internal 

 portions of the pulp consist throughout of an originally 

 granular or homogeneous, afterwards more fibrous matrix, con- 

 taining many rounded or elongated nuclei, which must be 

 regarded as a sort of connective tissue. Vessels are developed 

 in great numbers in the pulp at the period when ossification 

 commences ; the most numerous perpendicular loops of capilla- 

 ries of about O006"' existing in contiguity with the ossifying 

 surface. The nerves accompany the vessels, but are developed 

 later ; their number is very considerable and their distribution 

 resembles that in the pulp of the perfect tooth. 



The enamel organ [prganon adamantine), is applied to the 

 pulp like a cap by its internal, concave surface, and is con- 

 nected externally with the dental sac, in such a manner, how- 

 ever, that at the base of the pulp it presents a very small free 

 edge. Its structure is very peculiar. The principal mass 

 consists of anastomosing stellate cells (fig. 196, b.), or reticu- 

 lated connective tissue, containing in its meshes a great quan- 

 tity of fluid, rich in albumen and mucus. This gelatinous 



Fig. 197. Surface of the dentinal pulp of a newly-born infant : a, dentinal cells; 

 b, their appendages ; c, vascular part of the pulp ; x 300. 



ii. 5 



