3°4 



DIGESTIVE ORGANS. 



[sect. 141, 



a gradual transition by means of smaller cells between them and the 

 parenchyma of the pulp. Nevertheless in more vascular tooth-pulps, a 



Fig. 128. 



i 

 1 



A. Tooth-sac of the second incisor of an eight months human foetus, seen on its broad 

 surface; magnified 7 times, a. Tooth-sac; b. .enamel pulp; c. enamel membrane; d. 

 enamel ; e. dentine ; /. dentinal cells ; jr. boundary of the dentinal scale ; h. tooth-papilla ; 

 i. free border of the enamel-organ. JS. First incisor of the same embryo seen edgeways. 

 Letters as above ; d. dentinal scale in toto ; k. nerve and vessel of the papilla. 



certain limitation arises from this, that the capillary loops of the vessels do 

 not pass in between the cylindrical cells, but terminate close to each other, 

 underneath them, so that the designation of the layer of cells in question as 

 the dentinal membrane, membrana eboris appears to be warranted, especially 

 as these cells really yield the dentine. 



The inner parts of the pulp consist throughout of a more granular or 

 homogeneous, but subsequently more fibrous matrix, with numerous cell- 

 nuclei of a roundish or elongated form, which is to be regarded as a kind 

 of connective tissue. At the period of ossification, vessels are developed in 

 large numbers in the pulp, and the most numerous, perpendicularly deposed 

 loops of capillaries of about o-oo6'" are found principally upon the border 

 of ossification. The nerves accompany the vessels, but are developed sub- 

 sequently to them. Their number is likewise very considerable, and their 

 distribution in the pulp similar to that in the fully developed teeth. 



The enamel-organ, organon adamantines, embraces with its inner concave 

 surface the tooth-pulp in its entire extent, and is connected at its outer side 

 with the tooth-sac, but in such a manner, that it possesses a very small free 

 border at the base of the tooth-germ. Its structure is very peculiar. The 

 principal mass consists of anastomosing stellate cells (fig. 128 b.), or reticu- 

 lated connective tissue, which contains in its interspaces a large quantity of 

 fluid, rich in albumen and mucus. This gelatinous areolar tissue is thickest 

 immediately before the commencement, and in the first stages, of ossifica- 

 tion. Thus in the fifth and sixth months, it is T 4 S to § of a Vienna line, in 





