MAMMARY GLAND. 601 



others think it does not possess that spongy, cavernous 

 character of the true erectile, but resembles more the 

 dartoid structure. It is surrounded by an areola, which is 

 of a rose color in the virgin, and in the pregnant or lactat- 

 ing female becomes of a dark brown. Both the nipple and 

 areola present over their surface numerous small tubercles, 

 sebaceous follicles, and nervous papillae. Each tubercle 

 presents near its apex three or more foramina, which are 

 the openings of the excretory ducts from the gland com- 

 posing the tubercle, and whose secretion, it is believed, is 

 designed to protect the nipple from excoriation, while there 

 are some who regard these tubercles as lactescent. Be- 

 neath the skin and front surface of the mamma an abund- 

 ance of cellular tissue intermixed with globules of fat is 

 seen, which makes the volume of the gland appear much 

 larger than it really is. 



Structure. The mammary gland is surrounded by a cap- 

 sule of cellular membrane, which sends down processes 

 into its substance, separating and connecting its different 

 parts. It consists of lobes which are divided into lobules, 

 and these again into granules, about the size of millet 

 seed, which, under the microscope, are found to contain 

 vesicles. (Fig. I 1 ?.) The lobules give the exterior surface of 

 the gland a very uneven appearance, from being separated 

 at different depths, by irregular fossae which are filled with 

 adipose and cellular tissue. From the vesicles of the sev- 

 eral granules, the excretory or lactiferous ducts have their 

 origin. The ducts as well as the granules are known by 

 their white color. They converge from all parts of the 

 gland to the base of the nipple ; in their course, dimin- 

 ishing in number, but increasing in size. The termination 

 of these ducts, at the base of the nipple, is in sinuses, res- 

 ervoirs, or ampullae. As many as fifteen of these sinuses 

 are enumerated, having different diameters. From these 

 about twelve or twenty ducts pass through the nipple to 

 its extremity, and there open by as many orifices. These 

 ducts (Fig. 194) are lined by mucous membrane, and when 

 in a state of erection are doubled or folded upon them- 



