120 PRINCIPLES OP VETERINAEY SUBGSKt 



Describe the retention cyst ? 



These are the result of the retention of the secretion of a 

 gland. 



What forms of retention cysts are recognised ? 



1 . The sebaceous or atheromatous cyst, due to the dilata- 

 tion of a sebaceous gland. Seen in the skin of the horse above 

 the false nostril and internal canthus of the eye ; in the dog, 

 in the skin of the back. 



2. Mucous cysts are due to the dilatation of a mucous 

 gland. They may occur wherever a mucous gland exists. la 

 the horse, ox, nd dog the retention cyst of the sublingual 

 gland below or on the side of the tongue is termed ranula ; 

 retention cysts are further observed in the vagina of cows 

 (Bartholinine's gland); also on the lips in the trachea nasal 

 cavity. 



Retention cysts of large glands, due to the closure of a 

 number of ducts or of the main duct, especially seen in the 

 mammary gland of the cow, is termed a lacteal cyst. 



Describe the congenital, or dermoid, cyst. 



These are due to the inclusion of a bit of the epiblastic 

 layer in the mesoblast ; the wall of such a cyst may show all 

 the histological features of the skin. Dermoid cysts are met 

 with at the base of the ear of horses and cattle. A little 

 fistulous opening with a glairy discharge is seen ; the opening^ 

 leads to a cystic cavity containing a tooth. 



Describe the genuine cyst. 



These, also termed cystomata, are epithelial neof ormationEi 

 in glands with cyst formation. They have been observed ia 

 the parotid, mammary gland, thyroid gland and ovaries. 



