2QO SECRETION 



the great pectoral muscles. In women who have never borne children, 

 they usually are firm and nearly hemispherical, with the nipple at the 

 most prominent point. In women who have borne children, the glands 

 during the intervals of lactation are larger, are held more loosely to the 

 subjacent parts and often are flabby and pendulous. The areola of the 

 nipple, also, is darker. 



In both sexes the mammary glands are nearly as much developed at 

 birth as at any time before puberty. They make their appearance at 

 about the fourth month, in the form of little elevations of cutaneous 

 structure, which soon begin to send off processes beneath the skin that 

 are destined to be developed into the lobes of the glands. In the foetus 

 at term, the glands measure hardly more than one-third of an inch (8.5 

 millimeters) in diameter. At this time there are twelve to fifteen lobes 

 in each gland, and each lobe is penetrated by a duct, with but few 

 branches, composed of fibrous tissue and lined with cylindrical epithe- 

 lium. The ends of these ducts frequently are somewhat dilated ; but 

 what have been called the gland-vesicles do not make their appearance 

 before puberty. In the adult male, the glands are half an inch to two 

 inches (12.7 to 50.8 millimeters) broad, and ^ to i f an mcn ( 2<I to 

 6.4 millimeters) in thickness. In their structure, however, they pre- 

 sent little if any difference from the rudimentary glands of the infant. 



As the time of puberty approaches in the female, the rudimentary 

 ducts of the different lobes become more and more ramified. Instead of 

 each duct having but two or three branches, the lobes, as the gland en- 

 larges, are penetrated by innumerable ramifications which have gradually 

 been developed as processes from the main duct. It is important to re- 

 member, however, that these branches are never so abundant or so long 

 during the intervals of lactation as they are when the gland is in full 

 activity. 



Between the fourth and fifth months of utero-gestation, the mam- 

 mary glands of the mother begin to increase in size ; and at term they 

 are much larger than during the unimpregnated state. At this time the 

 breasts become quite hard, and the surface near the areola is somewhat 

 uneven, from the great development of the ducts. The nipple also is 

 increased in size, the papillae on its surface and on the areola are more 

 largely developed and the areola becomes larger, darker and thicker. 

 The glandular structure of the breasts during the latter half of preg- 

 nancy becomes so far developed, that if the child is born at the seventh 

 month, the lacteal secretion may be established at the usual time after 

 parturition. Even when parturition takes place at term, a few days 

 elapse before secretion is fully established, and the first product of the 

 glands, called colostrum, is somewhat different from fully-formed milk. 



