SPONTANEOUS NEOPLASMS IN MICE 



179 



tive tissue is more compact and may consist of one to several layers. These 

 connective tissue cells are wavy and thread-like in appearance, have 

 centrally placed spindle-shaped nuclei and possess pale eosinophilic cyto- 

 plasm. The nuclei are moderately pale, with somewhat evenly distributed 

 small chromatin granules. It is beneath this compact layer of connective 

 tissue that the loose stroma is found when present. Where the adenomatous 



Cyst 



Epithelium 



Edematous stroma 



Tip of papillary structure Cyst Blood vessel 



Fig. 92. — Papillary cystadenoma of the mammary gland (X200). 



structures are most compact the adjacent epithelial layers of different glands 

 may be in very close relationship with only narrow septa of stroma between 

 them. Large and small, irregularly shaped, thin-walled, endothelial lined 

 blood spaces are scattered throughout the stoma, most prominently in the 

 looser foci. The capsule is composed of a dense connective tissue layer 

 which may vary somewhat in thickness so that in some foci it is difficult to 

 distinguish. 



Polylocular cyst adenoma of the mammary gland. This type shows 

 many large and some small irregularly shaped, frequently intercommunicat- 



