Chap, xxxiii.] THE MAMMARY GLAND. 271 



Migratory or lympli corpuscles are to be met with 

 in the interalveolar connective tissue of both active 

 and resting glands. In the latter they are more 

 numerous than in the former. According to Creighton, 

 they are derived, in the resting gland, from the epi- 

 thelium of the gland alveoli. Granular large yellow 

 (pigmented) nucleated cells occur in the connec- 

 tive tissue, and also in the alveoli of the resting 

 gland, and Creighton considers them both identical, 

 and derived from the alveolar epithelium. And 

 according to this author, the production of these cells, 

 would constitute the principal function of the resting 

 gland. 



The large ducts as they pass from the gland to 

 the nipple, acquire a thick sheath, containing bundles 

 of non-striped muscular tissue. These latter are de- 

 rived from the bundles of non-striped muscular tissue 

 present in the skin of the nipple of the breast. 



The small ducts in the lobules of the gland tissue 

 possess a membrana propria, and a lining a single 

 layer of longer or shorter columnar epithelial cells. 



The terminal branches of the ducts, i.e., just before 

 these latter pass into the alveoli, are lined with a 

 single layer of flattened pavement epithelium cells ; 

 they are analogous to the intermediary portion of the 

 ducts of the salivary glands (see Chap. XXII.). 



365. Each of these terminal branches divides and 

 takes up several alveoli (Fig. 144). These are wavy 

 tubes, saccular or flask-shaped. The alveoli are 

 larger in diameter than the intralobular ducts. Each 

 alveolus in the active gland has a relatively large 

 cavity, varying in different alveoli ; it is lined with a 

 single layer of polyhedral, granular-looking, or short 

 columnar epithelial cells, each with a spherical nucleus ; 

 a membrana propria forms the outer limit. This mem- 

 brana propria, like that of the salivary, lachrymal and 

 other glands, is a basket-work of branched cells. 



