MAMMARY GLAND. 



In a gland which lias ceased to function, the interstitial 

 connective tissue becomes relatively more abundant and the 

 gland alveoli tend to disappear. 



The ducts are lined with a single layer of cylindrical epi- 

 thelium, which in the neighborhood of the external orifice 

 passes over into stratified flat epithelium. Outside, the duct 

 is clothed with a circular layer of connective tissue contain- 

 ing elastic fibres. 



During the climacteric the gland undergoes involution, the 

 alveoli and ducts decreasing greatly in number and size. 



The skin of the nipple and its near neighborhood is strongly 

 pigrnented. It contains large papilla and smooth muscle 

 cells which run in part circularly around the openings of the 

 ducts and in part longitudinally in the nipple. The skin of 

 the region immediately around the nipple (areola) contains, 

 besides large sweat glands, many (about twelve) sebaceous 

 glands of considerable size, the so-called Montgomery's glands 

 (glandulse areolares). The structure of the latter forms a 

 transition between the sebaceous and mammary glands. They 

 increase in size during pregnancy. 



The blood-vessels entering the gland parenchyma from 

 different sides break up into a fine capillary plexus, which 

 surrounds the gland ducts and alveoli. The lymph-vessels 

 run in the form. of capillary networks, both in the interstitial 

 connective tissue and in the skin of the nipple and areola. 

 The nerves entering the -mammary gland in part supply the 

 blood-vessels, and partly end in the gland parenchyma, as 

 in the salivary glands. In the skin of the nipple and in the 

 end dilatations of the larger ducts there are found Meissner's 

 and Vater-Pacinian tactile corpuscles (W. Krause). 



The secretion of the mammary gland the milk is an 

 emulsion of fat droplets, whose size varies from 1 to 5 /u in 

 diameter. Each fat globule is surrounded by a layer of casein, 

 which prevents their coalescence with one another. 



The colostrum, which is present in the mammary gland 

 before and in the first two or three days after the birth of the 

 child, contains fat drops and colostrum corpuscles. These 



