284 MICROSCOPIC ANATOMY OF THE TEETH 



the formation of orthodentine, and are arranged very much 

 in the same manner, but a careful examination of a thin 

 section shows that there are no nuclei, and that the tissue 

 composing this layer is made up of fibres and not cells 

 (fig. 181). 



Rounded or polygonal cells are, however, to be seen lying 

 among them in places which have a strong resemblance to 

 osteoblasts. The absence of odontoblasts would appear to 

 be consistent with the absence of dentinal tubes in vaso- 



FIG. 181. Connective-tissue fibres lining pulp cavity of Hake 

 (Merluccius). Ground Weil section (unstained). ( x 150.) 



dentine, as the typical odontoblast is provided with a process, 

 the dentinal fibril, which is not found in vasodentine. In 

 teeth in which orthodentine is found in one portion of the 

 tooth, while the rest is composed of vasodentine, as in the 

 flounder, odontoblasts are seen in the area of the pulp tissue 

 beneath the tubular dentine, although absent farther down, 

 where vasodentine has taken its place. Tomes had at first 

 considered that this layer around the pulp consisted of 

 elongated odontoblasts, but after a reconsideration of his 

 own and the author's preparations, he agreed that there 

 was no evidence of this, and that it really is composed of 



