404 



Tumors. 



2 — Surface cell cancers of nnicoiis meuihranes covered with cyl- 

 indrical epithelium (cylindrical cell cancers). 



3 — Glandular cell cancers [carcinomata]. 



Squamous epitheliomata, originating from the skin and mucous 

 membranes covered with squamous epitheUum, manifest their epi- 

 theUal proHferation by forming soHd cords of cells penetrating the 

 deeper tissues, these cords for the most part made up of cells of the 

 type found in the stratum ^Nlalpighii. The prickle and ridged borders 

 of the cells, the protoplasmic processes extending through the in- 



Fig. 121. 



Secondary carcinomatosis of serous surface of liver and omentum of horse ; 

 primary growth of cancer in the ovary. 



tercellular cement (so-called intercellular bridges) are usually well 

 marked, and the cells are arranged in layers as over the papillary 

 layer of the cutis ; and in consequence we usually find' the cells next 

 to the stroma of the tumor of a cylindrical form, the next layers 

 cubical, and the inner parts of the cord occupied by squamous cells. 

 The epithelium in its growth has no opportunity for desquamation 

 in these connective tissue spaces, and the old and first formed layers 

 must necessarily be found in the central part of the plug-like cord ; 

 being derivatives of epithelium subject normally to keratous 

 change, the cells of a squamous epithelioma usually also undergo 



