384 HISTOLOGY OF THE MORBID PROCESSES. 



type of a developing gland in the same sense as a sarcoma is 

 analogous to developing connective tissue. 



As a result of this structure, sections of carcinomata appear to 

 be composed of alveoli, which are filled with epithelial cells and 

 have walls of fibrous tissue. The character of the epithelium 

 depends chiefly upon the variety from which the tumor sprang. 

 The sizes of the alveoli and the amount of fibrous tissue that sepa- 

 rates them from each other vary in different tumors, and the carci- 

 nomata are divided into rather ill-defined groups, according to the 

 relative abundance of the epithelium they contain as compared with 

 the amount of fibrous tissue They are also subdivided according to 

 the character of the epithelium. 



a. MEDULLARY CARCINOMATA (Fig. 352) are those in which 



FIG. 352. 



Medullary carcinoma of the mammary gland. (Hansemann.) The stroma of the tumor is 

 here reduced to a minimal amount of areolar tissue containing the vascular supply of 

 the growth. 



there is the least amount of fibrous tissue. The alveoli are usually 

 large and filled with polyhedral cells. The fibrous tissue of the 

 alveolar walls may be so reduced in amount as virtually to serve 

 merely as a support to the bloodvessels it contains. Such tumors 

 are soft, of rapid growth, and very prone to degenerative changes 

 and metastasis. 



6. SIMPLE CARCINOMATA contain about an equal amount of epi- 

 thelial and fibrous tissues (Fig. 353). 



c. SCIRRHOUS CARCINOMATA (Fig. 354) are characterized by 

 small alveoli separated by large quantities of dense fibrous tissue. 



