STRUCTUEE OF MAMMARY GLAND. 



225 



Fig. 96. 



epithelium. The ducts converge toward tKe nipple, opening upon it by 

 10 or 15 apertures, and in their course dilating into ampullae, of small 

 capacity in women, but in the cow capable of holding a quart. 



As regards its development, the mammary 

 gland originates in the fourth or fifth j ts develop- 

 month as a papillary projection of the ment - 

 mucous layer of the epidermis, as shown in Fig. 

 96, in which 1 is the rudimentary gland in the 

 male embryo of five months, a being the horny, 

 b, mucous layer of the epidermis ; c, process of 

 the latter, the rudiment of the gland ; d, fibrous 

 membrane round it. At 2 is the lacteal gland 

 of a female embryo of seven months, een from 

 above : a, central substance of the gland ; b, <?, 

 budding outgrowths, the rudiments of the gland 

 lobes. (Kolliker.) 



Fig. 97, vertical section of the human mam- 

 a, its pectoral surface ; b, b, skin on surface of the gland ; 

 c, skin of nipple ; d, lobules and lobes of gland ; e, lac- 

 tiferous tubes passing from the lobules to the nipple. 



As pregnancy advances, the cells of the gland begin 

 to contain fat, in a manner not unlike that which is re- 

 marked in the cells of the sebaceous follicles of the skin. 

 When the gland becomes active after parturition, it is 

 stated that the first-formed milk-cells break up in the 

 lactiferous ducts into milk globules, their membrane and 

 nucleus disappearing. The milk globules are minute 



Development of the mammary 

 gland. 



mary gland 



Fig. 97. 



section of the human 



mammary gland. 



particles, varying in their diameter from the 





to the iSQQQ of an inch. They con- 

 sist of oily material inclosed in an envelope, as is shown by the fact that, 

 though they will resist for a short time the action of sulphuric ether, 

 Fig. 98. they are finally dissolved by that substance. Be- 



sides these milk globules, there are other exceed- 

 ingly minute fat particles present. The milk 

 which is first secreted after delivery contains cor- 

 puscles of considerable size, and of a granulated 

 appearance, as seen in the photograph, Fig. 98. 

 They are called colostrum corpuscles. 



r 111- ,1 i ^i f Colostrum. 



They are soluble in ether, and therefore 

 Miik with coiostrai corpuscles. con tain fat. There is reason to suppose that all 

 the fat globules of the milk are inclosed in cyst-like pellicles of casein. 



In the chapter on food (Chapter II.), a general description of the char- 

 acter and constitution of milk has been given, together with its physio- 



P 



