THE GENERATIVE ORGANS. 211 



terminating in blind or in more or less pouched or 

 dilated extremities ; these lie imbedded in connec- 

 tive tissue, which makes up the greater part of the 

 bulk of the gland. At puberty the gland of the 

 female undergoes considerable development ; well- 

 defined alveoli are found in the periphery of the 

 gland connected with the excretory ducts, but the 

 interstitial tissue is still more abundant than the 

 gland-tissue proper. Essentially in this condition 

 the gland usually remains until the climacteric 

 period, if pregnancy does not occur. 



If, however, the individual becomes pregnant, the 

 number and size of the alveoli rapidly increase ; the 

 ducts, which in the virgin terminate only in dilated 

 extremities, become connected with extensive groups 

 of newly-formed alveoli ; the gland assumes a lobu- 

 lated character, the connective tissue between the 

 alveoli is very much less abundant in proportion to 

 the gland tissue, is looser in texture, and contains a 

 great number of larger and smaller cells, and fre- 

 quently fat-cells. During lactation the alveoli are 

 very large, their epithelium contains fat-droplets in 

 considerable number, and fat is found in greater or 

 less quantity in the dilated cavities of the alveoli, 

 and in the excretory ducts. When the secretory 

 activity of the gland ceases, it undergoes involution, 

 the alveoli become smaller, fat ceases to be produced 

 by the cells, and the interstitial connective tissue 

 becomes proportionally more abundant. 



