532 



TUMOES. 



tions in embryonal development the formation of an imperfect 

 foetus in one perfectly developed, or intrauterine isolation by 

 constriction of parts of the embryonal body. These cysts contain, 

 besides epidermal tissue, hair-pouches, hairs, and also sebaceous 

 and sudoriparous glands, cartilage, bone, and teeth. Such tumors 

 were observed in the subcutaneous tissue, concreted with the 

 periosteum, in the orbit and its vicinity, in the testes and the 

 ovaries, rarely in other organs. Dermoid cysts have also been 

 observed in the lateral regions of the neck, and, as has been 



FIG. 220. FORMATION OF CYSTS IN MYXO-ADENOMA. 

 NASAL POLYPUS. 



M, myxomatous connective tissue ; G, mucoid degeneration of the epithelia of an aciuous 

 gland a future cyst. Magnified 400 diameters. 



suggested by Roser, are due probably to an imperfect retro- 

 gression of the gill canals of the embryo. Some of the cysts, 

 occurring at the base of the oral cavity beneath the tongue, 

 and termed ranulce, are considered dermoid cysts, especially 



