440 MANUAL OF HISTOLOGY. 



of rapid growth and development already alluded to. In ex- 

 ceptional instances, however, lacteal fluid may be secreted 

 during the extra-puerperal period. 



The mammae belong to the class of compound acinous or race- 

 mose glands, and, like the other organs of this group, consist of 

 a framework or stroma, and a proper secreting structure or 

 parenchyma. As they appear to the naked eye, the bulk of 

 the breasts is not their secreting parenchyma, but ordinary 

 adipose tissue. This fills out the intervals between the lobes 



and lobules, and gives to the entire 

 organ its smooth, round form. The 

 different lobes have separate secretory 

 ducts, which open upon the nipple. 

 These ducts ramify throughout the 

 substance of the gland tissue, and 

 ultimately carry upon their terminal 

 branches the clusters of secreting vesi- 

 cles, called acini or alveoli. Accord- 

 ing to Zocher and Hen nig, the true 

 glandular substance has not a rounded 



Flo. 189. Terminal vesicles and , 1,1 j ^i 



oma from the giand of a nursing shape, but shows a grouping into three 



woman. Langer. .. ,,... /> i i 



principal divisions, one of which ex- 

 tends far up in the direction of the axilla. It is separated 

 from the axillary lymphatic glands only by a small amount of 

 adipose tissue. This would explain the ease, readiness, and 

 frequency with which these glands become implicated in ma- 

 lignant disease of the mamma. 



Since the glands at birth differ very widely from the mammae 

 of adult women, and still more widely from those of pregnancy, 

 it will be convenient to consider the histology of the organ under 

 different aspects. This will be necessary, however, only with 

 regard to the acini and the epithelia therein implanted, as these 

 alone show such wide morphological divergencies in the dif- 

 ferent phases of existence. 



The nipple (teat, mamilla, papilla mammcB) is the one struc- 

 ture belonging to the mamma which is least liable to modifica- 

 tions of tissue due to age and sex. It generally assumes the 

 shape of a pigmented conical or cylindrical projection, at the 

 apex of which the galactophorous ducts have their terminal 

 openings. It is composed principally of a rather loosely woven 

 connective tissue, containing abundant corpuscles, and provided 



