TUMORS. 293 



3. Radicular odontomata are those derived from the dental 

 papilla, developing- from the roots of a tooth after the crown 

 has formed. They appear as bonv masses and are frequently 

 enclosed within the maxilla. Structurally, they consist of den- 

 tine and cementum, the dentine usually being 'surrounded by a 

 cemental capsule. They are occasionally observed in domestic 

 animals, being most common in boars. 



■i. Composite odontomata are composed of varying amounts 

 of irregularly arranged enamel, dentine and cementum. A single 

 tumor may contain several teeth fused into one mass. Their 

 structure varies with the amount of each of the above named 

 constituents they contain. Thus they mav be almost entirely 

 enamel or contain a very little enamel Tliey may be s.ilid and 

 massive or cystic. They are very likely to cause suppuration 

 and necrosis of the adjacent tissues. This type of odontomes 

 occurs more frequentlv in the horse. 



Dentigerous cysts are more properly classified as a type of 

 teratomata and will be discussed with that group of tumors. 



NEUROMA. 



Neuromata are t amors composed of nerve tissue. They are 

 exceedingly rare. They occur in connection with ganglionic 

 cells and most frequently those of the sympathetic ganglia, al- 

 though they may occur in the brain. They appear as nodular 

 growths varying from the size of a pin head to that of an apple 

 They are gray or wdiite in color, rather firm, and usualh- sur- 

 rounded by a capsule. Irregularlv shaped ganglionic cells inter- 

 posed with some nerve fibres constitute their minute structure. 



These tumors should be differentiated first from the so-called 

 "amputation neuromata," which are simply an entangled mass 

 of regenerated a.xones and are not tumors ; second irom fibromata 

 that develop from the perineurium or endoneurium of a nerve 

 trunk. 



Neuromata may be multiple but they are benign. 



ANGIOMA. 



These are vessel tumors that are developed independently of 

 pre-existing vessels. But it is frequently impossible t(T deter- 

 mine whether the mass of vessels is a result of excessive gniwth 

 of the pre-existing vessels (hyperplasia) or whether the}- are 

 newly-formed vessels. 



Possibly angiomata should be discussed under the caption of 



