STRUCTURE OF THE MAMMA. 



487 



having adipose tissue penetrating bet-n-een them. Each of these lobes 

 is provided with an excretory duct, and is subdivided into smaller lobes, 

 and these again into smaller and smaller lobules, which are flattened 

 or depressed, and are united bj areolar tissue, blood-vessels, and ducts. 

 The substance of the lobules is of a pale reddish cream-colour^ 

 especially as contrasted with the adjacent fat, and is rather firm. It 

 is composed principally of the vesicular commencements of the lacti- 

 ferous ducts, which appear like clusters of small rounded vesicles, 

 having a diameter from ten to thirty times as great as that of the 

 capillary vessels by which they are surrounded. These vesicles open 

 into the smallest branched ducts, which, uniting together to form others 

 of larger size, finally end in a single excretory canal corresponding 



Fi?. 341. 



Fig. 341. — Dissection of tkk lo-^ver half of the Female Mamma durinq the 

 PERIOD OF Lactation (from Luschka). g 



a, a, a, undissected part of the mamma ; 1, the mammilla ; 2, areola ; 3, sub- 

 cutaneous masses of fat ; 4, reticular loculi of the connective tissue which support the 

 glandular substance and contain the fatty masses ; 5, three lactiferous ducts passing 

 towards the mammilla where they open ; 6, one of the sinus lactei or reservoirs ; 

 7, some of the glandular lobules which have been unravelled ; 7', others massed together. 



to one of the chief subdivisions of the gland. The canals formed 

 thus are named the gaJactophorous duds, and are from fifteen to 

 twenty in number ; they converge towards the areola, beneath which 

 they become considerably dilated, especially during lactation, so as to 

 form amjniUce- or sinuses two or even three lines wide, which serve as small 

 temporary reservoirs for the milk. At the base of the nipple all these 

 ducts, again reduced in size, are assembled together, those in the centre 

 being the largest, and then proceed, side by side, surrounded by areolar 

 tissue and vessels, and without communicating with each other, to the 

 summit of the mammilla, where they open by separate orifices i these 

 orifices are seated in little depressions, and are smaller than the ducts 



