542 OF SECRETION. 



b. The gland itself is composed of the union of a number of glandules, which are con- 

 nected by means of the fibrous or fascial tissue of the gland ; it is between these, that 

 the mammary tubes may be observed to ramify; and from them their branches spring. 

 When the glandules are filled with injection, and for a long time macerated in water and 

 unraveled, they are found to be disposed in lobuli; and when a branch of a mammary 

 tube is separated, with the glandules attached, the part appears like a bunch of fruit 

 hanging by its stalk. When the lactiferous tube proceeding from a glandule is minutely 

 injected, the latter will be found to be composed of numerous follicles, in which the ulti- 

 mate ramifications of the former terminate, or rather originate. Their size, in full lacta- 

 tion, is that of a hole pricked in paper by the point of a very fine pin ; so that the follicles 

 are, when distended with quicksilver or milk, just visible to the naked eye. At other 



times, however, the follicles do not admit of being injected, 

 Fig. 161. though the lactiferous tubes may have been completely 



filled. They are lined by a continuation of the same mem- 

 brane, with that which lines the ducts ; and this possesses 

 a high vascularity. The arteries which supply the glan- 

 dules with blood, become very large during lactation ; and 

 their divisions spread themselves minutely on the follicles. 

 From the blood which they convey, the milk is secreted 

 and poured into the follicles, whence it flows into the ducts. 

 From the researches of Mr. Goodsir it appears, that, in 

 common with other glandular structures, the inner surface 

 Termination of portion of milk- of the milk-follicles is covered with a layer of epithelium- 

 duct in follicles ; from a mercurial cells ; which, being seen to contain milk-globules, may be 

 injection, by Sir A. Cooper; en- without doubt regarded as the real agents in the secreting 

 larged 4 times. process. Absorbent vessels are seen to arise in large 



numbers in the neighbourhood of the follicles; their func- 

 tion appears to be, to absorb the more watery part of the milk contained in the follicles 

 and tubes, so as to render it more nutrient than it is as first secreted; and also to relieve 

 the distension which would occur during the absence of the child, from the continuance 

 of the secreting process. 



c. The Mammary gland may be detected at an early period of foetal existence ; being 

 easily distinguishable from the surrounding parts, by the redness of its colour and its 

 high vascularity, especially when the whole is injected. At this period, it presents no 

 difference in the male and female; and it is not until near the period of puberty, that any 

 striking change manifests itself, the gland continuing to grow, in each sex, in propor- 

 tion to the body at large. About the age of thirteen, however, the enlargement of the 

 gland commences in the Female; and by sixteen years, it is greatly evolved, and some 

 of the lactiferous tubes can be injected. At about the age of twenty, the gland attains its 

 full size previous to lactation; but the milk-follicles cannot even then be injected from 

 the tubes. During pregnancy, the mammse receive a greatly-increased quantity of blood. 

 This determination often commences very early, and produces a feeling of tenderness 

 and distension, which is a valuable sign (where it exists in connection with others) of 

 the commencement of gestation. The Areola at this time becomes darker in its colour, 

 and thicker in substance, and ,more extended; its papillae become more developed, and 

 the secretion from its follicles increased.* The vascularity of the gland continues to 

 increase during pregnancy; and at the time of parturition, its lobulated character can be 



Distinctly felt. The vesicles are not, however, developed sufficiently for injection, until 

 lactation has commenced. After the cessation of the catamenia from age, so that preg- 

 nancy is no longer possible, the lactiferous ducts continue open, but the milk-follicles are 

 incapable of receiving injection. The substance of the glandules gradually disappears, 

 so that in old age only portions of the ducts remain, which are usually loaded with 

 mucus; but the place of the glandules is commonly filled up by adipose tissue, so that 

 the form of the Breast is preserved. Sir A. Cooper notices a curious change, which he 

 states to be almost invariable with age, namely, the ossification of the arteries of the 

 breast, the large trunks as well as the branches ; so that their calibre is greatly dimi- 

 nished, or even obliterated. 



d. The Mammary gland of the Male is a sort of miniature picture of that of the female. 

 It varies extremely in its magnitude, being in some persons of the size of a large pea; 



* This change is greatly relied on by many Obstetricians, as an unequivocal Sign of 

 Pregnancy. It is probably one of the best single signs, to which the medical man can 

 have recourse, in the early months ; but it must not be implicitly relied on. The change 

 of colour varies in degree in different individuals ; and all the alterations referred to may 

 take place, when the uterus is distended by hydatids, fibrinous concretions, &c., as 

 occurred in a well-marked case within the Author's own experience. 



