io8 



HISTOLOGY 



Recently von Korff, with special methods, has demonstrated another 

 sort of fibers which lie between the odontoblasts and pass from the pulp 

 into the predentine (Fig. 97, A). The fibers are apparently collagenous 





FIG. 96. 



Six odontoblasts with dentinal (or Tomes's) 

 fibers, f. p., pulp processes. From the pulp 

 at birth. X 240. 



A B 



FIG. 97. THE DEVELOPMENT OF DENTINE 



IN PIG EMBRYOS. (After v. Korff.) 

 d., Calcified dentine; e. c., inner enamel 



cells; f., fibrous ground substance of 



dentine; od., odontoblasts; p., mesen- 



chymal cells. 



and among them, immediately beneath the layer of enamel cells, cal- 

 careous granules begin to be deposited (Fig. 97, B). These granules be- 

 come abundant, and fill the ground substance of the dentine. Von Korff 

 concludes that it is not the odontoblasts but the fibrils | 

 of the pulp which give rise to the dentine, and similarly' 

 he finds that in bone the osteogenic fibers develop from 

 the surrounding mesenchyma rather than from osteo- 

 blasts (Arch. f. mikr. Anat., 1907, vol. 69, pp. 515-543). 

 Studnicka agrees with von Korff that "the odontoblasts 

 are really gland cells, which are only secondarily con- 

 cerned in the formation of dentine and do not produce 

 ground substance; their processes (the Tomes's fibers) 

 serve to convey certain nutrient material to the parts 

 far removed from the inner surface, and thus nourish 

 the dentine." (Anat. Anz., 1909, vol. 34, pp. 481-502.) 

 Von Ebner, however, maintains that von Korff's fibers 

 are produced by the odontoblasts as part of the process 

 of dentine formation. 



Other very fine collagenous fibrils in the dentmal 

 matrix are arranged like the decussating fibers in the 

 lamellae of bone. They cross one another as they run 

 longitudinally in the successively deposited layers of 

 dentine. These layers are sometimes marked out by distinct contour 

 lines, the direction of which is shown in Fig. 98. They indicate the shape 

 of the entire dentine at various stages in its development, and show that 



FIG. 98. DIAGRAM OF 

 THE ARRANGEMENT 

 OF THE DENTINAL 

 LAMELLA AND 

 CONTOUR LINES IN 

 AN INCISOR. (Koel- 

 liker.) 



