THE TEETH. 



641 



single medullated nerve-fibers, diverging from the longitudinal direction and 

 running obliquely through the pulp-tissue. In transverse sections of the pulp 

 it often happens that the nerve-fibers fall out, and then we see a roundish, 

 empty space bounded by the sharply defined 'external perineurium. The 

 absence of an endothelial coat renders such spaces easily recognizable in 

 contradistinction to blood-vessels. 



The main mass of the pulp is composed of a delicate fibrous reticulum, 

 containing a large number of bright, shining corpuscles. Longitudinal sections 

 in many instances exhibit delicate fibrous bundles scattered throughout the 

 reticular structure of the pulp, mainly in the neighborhood of larger blood- 



FIG. 279. PULP OF A MOLAR. LONGITUDINAL SECTION. 



M, myxoinatous tissue ; V, vein ; N, bundle of medullated nerve-fibers ; C, capillary 

 blood-vessel ; U, granular layer of basis-substance ; F, non-medullated terminal nerve-fibers ; 

 O, layer of odontoblasts. Magnified 200 diameters. 



vessels and nerve-bundles. Pulps composed of a fibrous connective tissue 

 only are exceptional, and, without relation to the age of the person, very 

 probably the result of morbid processes. Toward the outer surface of the pulp 

 the reticular structure, as a rule, is denser than in the middle portions. This 

 peripheral part is surrounded by a wreath of elongated formations, arranged 

 in a radiating manner, the so-called " odontoblast layer." (See Fig. '279.) 



Higher amplifications of the microscope reveal a minute reticular structure, 

 consisting of delicate fibers, or anastomosing bioplasson cords, with very 

 41 



