314 



Veterinary Obstetrics 



large amount of fluid formed within the folHcle, which may cause 

 the destruction of the tooth germ and may become enormously 

 increased, to the extent of one, two or more pints of fluid and, 

 when in the upper jaw, may cause serious distress to the animal 

 by projecting into the sinuses and interfering with respiration. 



Fig. 45- 

 Fig. 45. Sa<jittal section of superior molar^i of adult horse show- 

 ing on the left, normal development, on the right, arrested de- 

 velopment of the cement area. 



Fig. 46. A, Crown, and B, Longitudinal cross section of a super- 

 ior grinder of adult horse showing absence of cement in central 

 infundibulum and erosion of the enamel and dentinal plates. 



C, External cement. C^, Central cement area. 



E, External enamel layer. E', Central enamel. E'^, Ex- 

 ternal enamel at point of contact between adjacent molars. 

 The adjacent enamel laminiu project above the surround- 

 ing tissues, have no cement between them and are so ar- 

 ranged as to prevent the impaction of food particles be- 

 tween. 



D, Dentine. Er, Erosion area. Er', Erosion canal penetrat- 

 ing the tooth fang. 



P, Pulp cavity. S, vSuperior maxillary bone. 



These aberrations we know as follicular cysts. In other cases, 

 the walls of the follicle form an abnormal amount of cement, 

 which causes a very great accumulation of this substance, to 

 constitute what we know as a cement tumor, or cementoma. 



