THE FEMALE KEPEODUCTIVE OKGANS 



545 



muscle fibers are also found. These are arranged in circular bundles 

 at the base of the nipple, with longitudinal fibers within its substance 

 which, at the base of the mammilla, di- 

 verge in radiating bundles into the sub- 

 cutaneous tissue of the areolar zone. Con- 

 traction of these fibers elevates and hard- 

 ens the nipple, thus simulating the action 

 of the erectile tissues. 



According to Liperovsky (Anat. Anz., 

 45, 20, 1914) elastic fibers are more abun- 

 dant than was formerly recognized in the 

 walls of the alveoli and in the interalveo- 

 lar connective tissue, frequently in inti- 

 mate association with smooth muscle cells. 

 Such 'elastico-muscular apparatus' is well 

 developed in the peripheral portion of the 

 glands, in the subpapillary layer of the 

 skin, and especially in the vicinity of the 

 nipple. The elastic fibers, which are super- 

 ficially distributed, appear embedded at 

 their deeper ends in the muscle fibers. 

 This peculiar arrangement of elastic fibers 

 in relation to smooth muscle probably aids 

 in the expulsion of the secretion. 



Embedded in the subcutaneous tissue 

 of the areola are also a number of small 

 accessory lactiferous glands known as the 

 Glands of Montgomery (Areolar Glands of 

 Duval). The nipple and areola contain 

 also abundant sebaceous glands; and sweat 

 glands are present in the periphery of the 

 areola. 



The Resting Gland. With the cessa- 

 tion of lactation the glandular alveoli un- 

 dergo a rapid atrophy, and are replaced 

 by connective tissue derived from the inter- 

 lobular stroma. The ducts contract and 

 the epithelium piles up to form a two- 

 rowed, or even thicker, layer. The alveoli are reduced to mere buds 

 from the terminal ducts, and their lumen is almost obliterated; their 



FIG. 477. FROM A SECTION OF 

 THE HUMAN MAMMARY 

 GLAND IN THE RESTING 

 CONDITION. 



a, remnants of the glandular 

 alveoli; 6, duct; c, connective 

 tissue; d, adipose tissue. Hem- 

 atein and eosin. Photo. X 10. 



